I'd avoid the Chiappa. I saw nothing but malfunctions and poor precision with mine. I've been eyeballing a Tippmann pistol myself, but have a Tactical Solutions SBX upper I use with a cheap AR15 lower I've dedicated to it. I'd really take a CMMG upper on a PSA lower over a Chiappa any day, and it probably wouldn't cost any more. If you have any other AR15 lower laying around, you can just slap a .22lr CMMG, Spikes, Tactical Solution, or one of a few others right on it, and have readily available .22lr magazines as well.
I do have a couple of GSG MP5 style firearms, and they function fine, but the sights are hard to look through, and they don't shoot as tight of groups as the Tactical Solutions setup. It's not even close. They do look nice though.
Good luck.