MP7 is junk. The only good one on the market is TM. Others are cheap junk that break down. The Firepower / Aftermath / Well are all the same rebranded gun. Do a quick search of the forum and you'll hear a lot of firsthand accounts, and not many are good.
The TF11 is the only one that's been proven game worthy, although the Taurus pistol can hold its own as well. But of those, the TF11 is the only one I think is worthwhile.