Stinks you had connection issues... If you don't mind... When/where did you get your mvp 2? I use several toppers and have yet to have any connection issues. Knock on wood... I wonder if since I've only had mine a few weeks that maybe innokin has fix connection issue?
I've been eyeing the Zmax, found on a site for the chrome for $40, also been wondering about the groove II, as has a 3400mah battery and goes up to 6volts/15 watts.
I like the MVP2 for size and battery, but as I use a few different toppers, this connection problem really is a pain in the ...., if it wasn't for that, I probably wouldn't even be considering something else.