Gas guns for the win!
Love them all!
Sounds like with WE GBBR you need to replace every internal part with RA-Tech and spend more $ then you would just buying a better base as per @SuperHog?
WE GBB Pistols seem great though.
AEG's are more consistent and accurate in my opinion. Whereas gas guns, temperature and the amount of gas in your magazine can be prove to be very inconsistent., but then again, I don't find it fun nor realistic when your just camping in a brush holding down the trigger with 1-300 bb's in one magazine. I much rather the pleasure of my gun being loud and the kick.
Your other choice could be an EBB "electric blow back" - Look up the "KWA MAGPUL PTS RM4 ERG Electric Recoil SCOUT." It doesn't have the fancy bolt and such as normal gas guns, but does have a "bolt catch" function.