I just ordered one this week, so obviously I convinced myself... I've read around and the Vector's seem to have a very good reputation for quality and reliability. I though about a Vector Mini Uzi for a little while, but they are an extra $1000 and some people say the cyclical rate is too fast, can't easily let loose a 1-2 shot burst, plus at 1200 RPM a 25 round clip would go pretty fast.
Now I am working on getting a suppressor for it so I can shoot without hearing protection and freaking out neighbors, but I have a lot to learn about that world...
A have an AR15 and and FNC, and also thought about getting a 5.56 full auto, but I think I would prefer to keep them semi, and have a subgun as my class 3 'cause I figure it is more controllable, cheaper to shoot and can be shot in more places.