Well, I use discs and really don't want to switch back to rim brakes, for all the reasons given above. However, seems to me it's not "all gain, no loss". With f/r discs, you inherently have much more dishing both front and rear, in addition to rear drive-side dish if running a cassette. Thus, wheels are inherently quite a bit weaker -- no way around this. I don't worry much, running 26" (559 rims) wheels, but I would think a bit more of an issue with 700c?? Dunno, but intuitively strikes me as a consideration. I also second the comment about fork rigidity and ride quality; any rigid 700c bikes running discs that I'm familiar with do seem to have to have an overbuilt fork, to cope with the braking forces, relative to a version with rim brakes. Compare, e.g., a Trek Soho/disc with, e.g., a Trek fx bike, which uses v-brakes.