The V2 gear box works fine if you get a quality gun, ie. non-clone. Just as a V3 will seize up on semi unless you get something of quality. In both cases, any upgrading solves these issues.
Best to buy what you like and what offers the best possibilities for expansion. Winner by far are armalites, then AK's, then G36's, everything else is really hard to get anything cool for. Mags are also the same case with armalites having the best deals, then AK's, then G36, then Sig 55x's.
In Airsoft, you really do get what you pay for, except in the case of TM vs. JG. Elsewise, stay clear of cheap clones that are non-JG. If you are not budget minded, you can spend upwards of $3000 on a gun, as with paintbal, eh!
-Doug