I have and use Ksyrium elites and Cosmic SLs. If I could have only 1 set, it would be the elites. I still prefer an Al brake surface in the wet, because I feel the stopping power is much better than carbon, also the grit and crap you pick up when the road is wet tends to really abrade the carbon brake track. Along these lines, the sealed bearings on the mavic wheels will be a plus in the wet and if you tend to wash your bike a lot with water. I have three beefs with the cosmics. They're heavy to the point that its noticeable on long climbs, the ride is pretty harsh, and they catch a crosswind more than my Zipps, for example. With regard to the Ksyrium line, I went with Elites mainly due to the steel spokes. Although I haven't spent much time on SLs, I'm told that the interface between the lighter and thicker alloy spokes and the rim is beefier for strength, and therefore provides a harsher ride, and the wider spokes catches a crosswind more than the thinner steel spokes. If those spokes are turned, they can also have a detrimental aero effect. I don't know what the roads are like where you live, but my butt definitely preferred the Ksyrium elites to the cosmics on the pothole ridden Pittsburgh roads. Hope that helps you.