Yeah, 10mm is an effective caliber.
Personally I dont think it's different enough from others to justify its existance, but anytime theres a new caliber introduced, guns sell! And thus there will always be new calibers poping up every year, and a lot of people bit on 10mm... Worth adding!
Everyone remember (M25, Geesh! I'm impressed if you can effectivly use all those at the same time!), its a ONE GUN pole. Doesnt matter if you own it or not. Doesnt matter if you own any guns at all. Just a question of "From your knowledge and experience, what would your personal choice be?"