Rode the 25mm ProRace 2's on a set of HED Ardennes on my MXL for a couple hours yesterday and the ride was definitely different than on the Open Pro rims.
Cornering felt more secure, cushioning was a bit better (I think I was running them around 85-90lbs PSI and I am about 150-155lbs). I liked the feel a great deal and hope to get out again after the next few days of 30 degrees and icy roads.
Never having had a low spoke count wheelset before (these are 18 front, 24 rear), I probably won't use them for randonneuring, but club riding is perfect. A very nice wheelset and maybe even a bit better than my DT RR 1.1 set. The hubs are dreamy smooth, I could coast for considerably longer in places where I've done it previously. Sweet wheels.
What a great day to ride too!