I think at your weight Macha you could easily go with a 32 spoke wheel especially with a Sun Rhyno rim. I been riding with a pair of 32 spoke xt/ rhyno wheels ( from nashbar)on my rigid MTB with my weight of nearly 200 lbs for nearly two years without any problems other than a slight re-truing of the rear this spring. I have no personal experience with the mavic 519, I did read a complaint on another forum that claimed the 519 on thier bike was developing stress cranks around some of the spokes. I have never heard anyone else make this claim so I would probaly question it's validity.

I usually build my own wheels but I have to say the two sets of machine built wheels I have ( Nashbar on my MTB and Wheelsmith on my tandem) have never given me any problems.