ok well i own a TM G3-SG1 and i love the thing to death. yes it maybe be long for indoors (i dont much care i can shot accross our teams indoor feild without have to adjust for distance). it can be creeky but not has bad as must ppl say it does just to twist the damn thing in your hands. the bi-pod is alright its great for when u need a platform for aimming and as a support weapon (i love the 550 round hi-caps). the gun is a great gun stock i dont right now see any need to upgrades aside from a inner barrel, it shoots about 280-290 i think and if u want a gun that can be used as a sniper/assult/support the SG1 meets those for me. the only down side is not many rice parts compared to the M4/16 class, when you do put a metal body on it my god is it heavy, its not a very sling friendly gun from what i've read yet to test it myself but in my opioin i give a 8 outa 10 stars it meets what i want to do its something different from the 100's of M4's and really great gun stock.
if you like you should read the thread i started way back and read what ppl said about the gun
http://www.airsoftcanada.com/showthread.php?t=14471