Having used Fein 65,Fas 604, and various Fein,Walther,Steyr,Morini Pistols My best pistol was a Feinwerkbau C2 managed 570+ on my best days and the only thing wrong was the guy holding the grip.
It's all about how it feels in your hand, balance and trigger.
The only draw back to Co2 is can you get your bottle filled near you.
Enjoy your shooting
Friendly