I ride 25s and 23s...I've got a 25mm michelin carbon on the front and a 23mm rubino pro on the back, simply becuase the back michelin carbon wore out, and the front one didnt. When I went to the shop, there were no carbons in stock, but there were a few rubinos (an underrated tire, IMO) left, so I bought one.

honestly, I didnt see much difference in the 23 vs. 25. Perhaps the ride is a bit harsher, but not by a whole lot. I ride on hardpack dirt/gravel a fair amount, and I think that the big difference is not in size, its in construction. a 28mm version of a michelin pro light is gonna flat easier than a 23 mm michelin carbon.