I owned a Maiden Pro for about 20 months and only sold it so that I could get a JP Premium. Maiden is a great game but since I'm currently limited to only 4 modern pins in my line-up it was time to move on to something else and it made sense to trade one KME game for another. I think JP is a better/deeper game and the theme is way better for me. I wouldn't mind owning Maiden again in the future though if the right deal presented itself.
As far as Pro/Premium goes I've played both and for this game the Pro is the way to go at least for me. The Premium features aren't dynamic enough and require a lot of tweaking to make them work right and not be problematic. The Pro you just setup and play. When I owned my Pro I hardly ever even took the glass off. And the "Can I play with Madness" mode isn't a better option than adding 15 million to your Power Jackpot.