I’m 15st/16st and ride a variety of 29er wheels and have had no major problems with any of them.
Sun Ringle Chargers on my FS have been excellent and are the burliest of the lot (32h). Bonty Race Lites on the HT (28h) have been excellent also although the rear rim is a bit knackered now and loses tension, but that was due to me crashing it after forgetting to do the QR up properly – not the wheels fault! Have a SS specific Bonty on the back of the SS (32h i think) that has been fine and a Halo Freedom on the front which appears very strong but is no lightweight.
WMB (i think) has a review this week for some Novatec 29er wheels which they raved about. Fairly lightweight and around £300 i think.