I received mine a little over a month ago. Out of box, it worked great. It have above average compression and the ROF was nothing less than intimidating with my 9.6v 4700. Within 2.5 hours of play things stated to slip into "that" spiral.

PROS:
Very light weight (12 lbs loaded with .25g BBs)
Well balanced
Piston release lever
Two position spring guide
Can easily hold a 10.8v SC battery
Trigger pull is a nice change. You just need to try it, its heavier than normal but still crisp.
~3000 round mag that attaches securely and quickly
Excellent fit and finish and SOME VERY design
Quick disconnect barrel system includes inner barrel and hop-up unit
Solid sling attachments
VERY easy MB access (a latch and two screws)
Clear MB is neat to watch (strong but not for hybrids)
Ver. 2/3 gears, bushings

Cons:
Crap stock piston
AEG motor fried with 15,000 shots
box mag motor fried
box motor feed control switch fried
MB disassembles upside down (air nozzle points to the left due to design)
Nuts used to secure MB are not secure
Plastic MB
Plastic top cover
Plastic gas plug
Plastic carry handle mount (the ring around the barrel is plastic, WTF)
XYT gears
4 shims, F O U R SHIMS! WTF
Some internals are hard to determine compatibility (air nozzle, cylinder head)
Crap spring
Piston head is not ported
Prone to mis feed
2 6mm bearings on sector gear
Type 0 cylinder (it has a medium-short barrel)
Doesn't come with a battery
~30FPS compression leak between air nozzle and hopup

What I did since my purchase:
Two Alice Pack shoulder straps joined together for a sling
Prometheus shiims
Prometheus hard v2/3 piston
G&G L85 piston head (neat but not sure if it increases perfromance)
#14 o-ring w/ TM silicone and Guarder cylinder grease
Deans Ultra plugs
SW-AB Long MOSFET
Gaurder Infinite Torque motor (temp. until I get a SystemA Magnum)
PDI 140% spring (Piston is too heavy for SP1 (~350FPS) but it works great in SP2 (~375FPS). I suggest a 170% (~375/400, which is on the way).
KA POM sector chip (fixes feeding issue)
E-Flight 180 motor for box mag motor
Radio shack may have a normally open push button switch for the box mag (I have yet to fix this)
6v 1700 AA NiMh for box mag
Sorbothane cylinder head pad
SystmeA type 1 cylinder

What I plan to do:
Wild Monkey STAR M249 MB (requires modifications but allows hybrid upgrade performance)
SystemA Magnum motor short type
Extreme-fire Cheetah MOSFET
Wolf Dragon Project PCB board
12ga high end wire with Deans
Elite 11.1v 4800mah Lipo
Systema standard torque gears
Try Deep Fire P90 metal air nozzle (reason to believe it use Ver. 6 air nozzles)
PDI 170% or Prometheus MS135 spring (looking for ~400-450FPS options @ 20RPS)
Replace the feed control switch
STAR M60 railed top cover
Guarder ELKEN scope
GB-Tech steel carry handle
Steel Bushings (comes stock w/ 2 6mm bearing bushings on the sector gear)
I'm considering another box mag

Overall I'm happy but I would not recommend it to a friend unless they understood that its a starting point and it needs love. It reminds me of an ACM. I would not even consider telling anyone to purchase this AEG unless I knew they were SAW gunners or love M60 and could purchase one for $430 shipped. I'm sure there is more that I can think to say about my "60" but its the holidays and other than my friend Jameson, I'm up by myself. I'll update soon and let you guys know how my SAW is coming along. My goal is 20RPS @ 400 and 450FPS where FPS regs permit it. Pictures soon...

ARES will be releasing a full metal MB unit to replace the STAR's. They are also going to do the same for the STAR L85 series including the L86, FNC and M249 series. JOY!

This thing kicks @ss! Stainless steel parts and 8mm bearings. Maybe with this the STAR M60 will rival the CA M249, perhaps surpass it with greater battery storage.

I've got a few new bits on the way.

POLYRC 11.1v 4270mah 18c Lipo
SC CNC GS-B (Gen. 2) gears
SystemA magnum motor (short)
KM Taper 400-590mm cylinder
PDI 190% spring
SystemA air nozzle
STAR M60 Bearing spring guide
SW-Cheetah
WDP-PCB controler
Modify tempered steel 7mm bushings
4' of red & back 12ga wire

Ares complete metal gearbox is a must buy for the AEG. The internals will eventually end up in the trash but the gearbox is essential for high torque motors. The 8mm bearings is a huge plus too. I'll write more later about it but for now I'll just say that I would highly suggest a Ares M60 over a STAR.

New performance:

Parts:
8mm MB
prometheus shims
SP130 spring
Systema Magnum motor
SC-Balanced gears
prometheus hard piston
G&G L85 piston head
KA sector chip
STAR M60 bearing spring guide

Tuning:
shiming
Angle of enganment (AOE) correction on piston
2nd and 3rd to last tooth removed from piston
#14 o-ring and compression lube for piston head
compression lube for air nozzle
Systema magnum motor endbell insulation

On an Elite 8.4v 5000mah NiMH it shoots
38.4rps @ 390FPS

The kicker:
stock wires
stock bushings
no mosfet
8.4v 5k battery

Latter:
New box mag (might have to make one)
Kanzen bearings
11.1v 18c 4270mah lipo

I need more POWER

38.4rps with an 8.4v? Dang you must of put the Jesus touch to that gun. Good job

dang...u might want to keep a backpack full of bbs on you during a game.

Spending $60 on ammo for a day of play is starting to remind me of another hobby I use to have.

well it is your choice if you want to shoot at trees.

Support is not a role for those that want a lot of kills. Its ironic that you carry that much ammo, but you are intenionally shooting at people taking cover to advance you team. Support does get the treat of opening fire first in an ambush. My M60 will excelle in ambushes where dumping ammo is ideal. Having to reload durring suppressive fire is not good. We'll have to see.

how much $$ did you end up dropping in this beast??

Hmm... lets see

25 springs
5 shims
80 mosfet
35 pc
100 lipo
5 deans
175 mb
450 m60 & s/h
8 bearing spring guide
18 piston head
52 barrel
10 hopup
65 2nd mag
31 Poly mb
130 CNC'd gears
95 magnum

too much, $1284 for now. Some of that is from Christmas though. I still need to get the mag to feed the beast. I'll try to mod it with a hicap but if that doesn't work I might have to use a M249 MAG magazine.

There are a few other things I want for it.
Kanzen ceramic bearings
Railed feed cover
steel bipod
Elcan OS3.4 or M145 scope clone, I'd also consider a good ACOG clone
Belt of inert 7.62nato FMJ and tracer rounds (~10 rnds) for looks.

Probably another 300-400 before I can say its done. I'd still do this over an Inokatsu or VFC. Its only slightly more and you get better battery storage, MB and the AEG is lbs lighter. I also have internals that I picked out. No body sells AEGs with steel molydenum CNC'd gears.

Prometheus 407mm 6.03TBB and Prometheus bubking made a huge difference in compression. ARES box mag is a champ. Prometheus hard type piston stripped after an abusive 20k yesterday. It had 50k on not to mention the misfires that plauged my setup prior to the new mag. It was a used piston from the start, without AOE correction. I knew it wouldn't take too long. Working towards a hybrid setup with my lipo.

incorrected reported my ROF averages by useing hot batteries. I am getting HIGH ROF but my 8.4v when its not ~10v will not give me ~40rps.

Target perfromance with lipo
~450FPS or 1.8j at 30rps

I'll use .28s to achieve a brush cutting effect that will force players to seek hard cover instead of thick brush.

Target accuracy
my grouping opens up at 150'. This sucks considering my range with .28 and the power behind them. I'm going to try a hard type bucking and see.

Prometheus hard type bucking installed and now shooting ~445FPS with .2g. This is good compresion for my spring, a Guarder SP130 should generates about 430-460 depending on tuning. My joules in .2g is 1.81j, which is great. I'd like to check my joules in .25g and .28g just to see. I think it'll be higher than 1.81j. There is more to say about the concept of using high volume cylinders than normal. I never plan to use .2g so I would rather use a greater volume to appropriatly propel a heavier BBs. This is all due to the Marui boys and the copycats that couldn't think outside the box when given the oppertunity to optimize AEGs that were always destine to use heavier BBs outside Japan.