I've got a set of CXP-33s laced to Ultegra hubs, both 36 hole, 3-cross, 14ga spokes, brass nipples. I started riding on them when I was 240 or 250 pounds back over the summer. A deer wiped me out by running right into my front wheel when I was doing 25 mph on them in September.
They're still dead true.
I got them from Colorado Cyclist. I'd bought from them in the past and for my return to serious cycling wanted a totally bombproof set of wheels from someone I had dealt with in the past. I probably could have gotten them cheaper, but saving a few $$ wasn't at the top of my priority list.
I've since dropped to 210 lbs or so, and I'm currently riding Neuvations and they're a lot lighter. I can definitely feel the heavier weight of the Mavic rims when I accelerate or climb, but those Mavics are definitely bombproof.