if you're doing a century in a couple of weeks you might want to consider running the largest diameter tire your frame can accommodate. generally fatter is more comfortable and not noticeably slower. why would you want to run anything smaller than 25 anyway?
Purely anecdotal, but I ran a 1-1/4" rear tire on an mavic a719 touring rim, which is rather wide (24.5 outside per speedgoat.com), and never had any problems
edit: Open Pros are very nice rims though. Don't think you'd go wrong with either wheel