Yes, a 12 volt would suffice your stock M98.
Most places should be carrying the newest version by now, but it can't hurt to check with the supplier.
I believe the paddles are interchangable...in fact, I think the evolution paddles are stock in the new 12 volt.
As for problems, I can't help u there, I haven't had mine long enough to experience problems.
A 9 volt would probably also work on your M98, but if you can find a 12 volt within a resonable price range, buy it! Someday u might upgrade to a faster gun, and u will avoid replacing the 9 volt.