co2 weapons have the highest FPS of any stock airsoft weapon, co2 is like the LiPo of GBBs...
as far as hopup, pistols are notorious for bad hopup...but you have to think about the short barrels as well, which negates most possible benefits of hopup, which is why most pistols and shotguns have "fixed" hopup set for .2s
idk try to find some reviews, i would but i don't really care anymore, espec since its not permissible for a USMC load out
oh i have skirmish HFC gas revolvers (4in) and i will say they are useless for skirmishing, low power, low range, low accuracy,and lack of rounds.