I'm "only" about 195 lbs, and I STILL went with a 36-spoke rear wheel for my newest wheelset. I got Velocity Aerohead OS (offset) rear rims. In case you're not aware, the "center" of these rims (the apex of the aero shape, where the spokes enter) is offset to the non-cassette side, allowing the wheel to be built with less dish and therefore more uniform spoke tension on both sides of the wheel. Done properly, the resulting wheel can be a good bit stronger than one with a traditional design. And just go with 36 spokes. The resulting 20-gram (or so) savings over a 32-spoke wheel is less than two-hundredths of one percent of your total riding weight. Think you'll feel that?