Depends on what you mean by "feel".
PTW, GBBR (gas blow back rifle) dimensions are either spot on or very, very close to real steel. Both can be made ridiculously heavy by adding on steel parts here and there.
So far as the "shooting action" of them...the GBBR comes closest. I haven't touched/shot the TM SOPMOD (electric recoil)...so can't comment on those. I've shot/seen/worked-on the Guarder Auto-bolt (AK) system and G&G M4 blowback systems...they're utter gimicks and weak to the point that you'd be better off without it.
Having said that...a well built metal M4 AEG is very nice. The grip is a little wider/rounder than a real grip...to hold the motor. The body is a little wider...to hold the motor. Many start out very light...but changing up parts starts to add weight (i.e. a steel barrel adds a lot of perceived weight to the rifle). But having said that...unless you absolutely must have the exact dimensions...an AEG will be fine.
Really...the best thing is to get out to a game and chat it up with some of the guys. You'll probably be able to arrange a rental on the game thread.
Last edited by m102404; October 22nd, 2009 at 16:11..