Not true at all, with a grind and a decent set of pads rim brakes will work great in the wet, in fact mine work just as well as they do in the dry and the power is much greater than that of a disc. It really comes down to what you want, if you want modulation, an easier set up and no noise then go disc, if you want ultimate power go rim. My recommendation is disc on the front so you can control your speed easier and rim brake on the rear to avoid slip.