Loudness (potential stealth issues), Complexity (at first)
Low capacity for paint, (get a VL clip)
I've been after one of these markers for a while now, ever since I first saw one in about 1998. I finally got one last summer and it has been everything I hoped it would be. Something about fully automatic fire has always intrigued me. I aquired a Rainmaker a while back, one of the old models that was select fire, and I loved to shoot with it, unfotunately, it ran on C02 and that meant that extended full autoing tended to freeze the gun over, and it wasn't all together accurate. The local paintball outlet finally got a HPA fill system and I decided it was time to get an AT85. The first thing I did was put it into full auto and empty my clip. It's extremely satisfying to hear the bark and feel the kick when you squeeze the trigger, and everybody else on the field knows that someone is on the recieveing end of a lot of fire. I play alot of woods ball and the AT85 works perfectly there, I have yet to play speedball with it. I don't know how well a front player could manuever with it but it should work fine for a back guy.
I would say this is one of my best paintball investments, and believe me, there have been lots. Get a VL clip for it and its just like any other marker except more accurate, reliable and much more fun to shoot!