I've played both and have no doubt that the Premium is the better game, but the Pro is a great game by itself. Playing it at Texas last Spring, with very early code, you could still see what a fun experience it was. The theme, music, lights and art all compliment this great game design.
With GB, Stern rolled out another price increase and drive it north of $5k delivered NIB. As others have said in various threads, it's not just the price of a luxury item. It is the value for the money. As these prices rise, I'm not seeing the additional value for my money. I would likely go pro and used.
I had an original AC/DC Premium. It was an amazing game. I sold it to try new things for a very reasonable price. I would like to have another one. At the current asking price for that game, I'm just not interested.