If you've got a GBBR then run with it. I love my AEG to bits but if I get the chance I'll jump onto the GBBR bandwagon (well actually what I want to do is own a Classic airsoft with an external rig/hose). I'd still keep my AEG as a backup and cold weather gun though.
Don't worry about classic airsoft since they're expensive as hell but the pros are they don't suffer from cool down and you can use AEG mags, con's being that if something breaks then you're pretty much hooped.
I think a GBBR, if you're conservative with your shooting will be fine and can mitigate the cool down effect enough that it doesn't matter as much (ie you don't dump a whole mag in 5 seconds but instead maybe do a few short "three round bursts" and single shot firing).
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE