I played both IMDN Pro and the POTC Prototype at Golden State. POTC is the one I was willing to stand in line to play a few times. Awesome game! I wasn't interested in playing IMDN Pro again after the first time. Not my cup of tea.
You asked about a Premium though. I say find one and play it to see if it's worth the extra $ over a pro. You could always buy a Premium and sell it a year from now to help fund a Pirates (when they're finally available)