I vote Open-Pro. Judging from my own experience and anecdotal evidence from most other people, it seems that OP rims are one of the better choices for handbuilt wheels, for either training or racing. Once I settle an accident claim from a crash that I was in, I'm going to invest in a PT, and I'm fairly certain that I'll have it laced to a OP or equivalent. I was considering going aero and tubular (a Zipp rim, etc.), but that really doesn't make much sense considering how much training I do on ****ty Chicago streets.
I second waterrocket's idea of buying a PT hub for the Flashpoint down the road, or even buying a lighter rim and using that instead.
You have a lot of options – think most about what kind of riding you do and where you do it.