I'm late to this party but...
I have a decent sidearm.. the ASG CZ P09. It's pretty okay, accurate out to 50 or 60 yards (usually). It'll take a suppressor, and I have mags for both CO2 or GG.
But it is hard on gas. uses a lot. Granted, while operating in a sniper role, I should rarely even have to use it, but there's always that "one time when" scenario. It's also friggin' loud. When I'm running my AEG, I like that it's loud. But not while trying to be sneakybear.
I've been researching sidearms for the better part of 6 months... what I'm looking for is easy enough, right? Not so much. I'm looking for a CO2 NBB that will take a suppressor. And has a hopup. I'll be lobbing sniper-weight BBs with it, so I need the spin.