I finally got some decent time on DP this weekend. I played Prem and LE, not Pro. First off, the LE is nice but not worth the extra change in my opinion. Cosmetic upgrades don't move me to shell out more cash. Having said that, I thought the Prem was a lot of fun, and it has playfield/gameplay upgrades for the additional cost. I'm definitely considering that to be my next purchase. Not having played the Pro, I think I would be let down by it. The repeatable left loop was a serious rush, and it gives an additional mode not available on the Pro. I'll also take drops over stand-ups (even though you're paying for them).
I have a GB Prem, and I really enjoy it. However, it is not a novice pin. My wife and friends hate it. They don't know what to do (and aren't open to instruction), and when they shoot the "flashing lights" there is usually on one or two lit at any time. Moreover, it's not hit the flashing light over and over, you have to hit each light to advance. Needless to say, novices with bad aim get frustrated because their scores are usually pretty bad, and they don't get very far.
If it's for you and you know what you're getting into, I'd say GB Prem over DP pro. GB Prem just has too much going for it. A final update will make it better, but even without it, it's a great game and an awesome challenge.