You can use one but you're setting yourself at a distinct disadvantage.
I play against hi-cap, high ROF aegs all the time with gas rifle running 30 round magazines. I have to pick my shots while the rest of the group can lay down a constant spray of BBs.
It's my choice to leave the AEGs in the locker so I've got no one to blame but me when I get lit up. I prefer the picking my shots style of play though so I get what I'm looking for out of the game.
Airsoft, where nothing is hurt but feelings.