Want a nice wide and tough rim whilst still keeping it relatively light, will be setting 'em up tubeless as well. Are Flow's still the popular choice for 'All Mountain/Enduro' riding?
Flows sound like they would ideal for you or you could try the Arch if you want to save a little bit more weight
Yup, flows are your benchmark there really, that's what I'm using for what's probably much the same sort of riding and they've been flawless.
I like my Flows but getting the 2.35 High Roller on was bloody tough. Not looking forward to my first night ride puncture!
Currently got some Pro 3 and Pro 2 Flow's, Crest's (kind of a v.lightweight, mid-width version of Flow) and Bontrager Rythym's.
For my 88 to 90kg weight, I find the Flows are by far the best for rocky natural riding on a 5" travel bike. If you can afford the Hope Pro 3 SP/AM on Flows, they're well worth the money - very nice stiff and strong wheels. Doddle to go tubeless with Stans kit aswell.
Not sure why people are having trouble fitting tyres... I think you guys might cry if you tried getting my double ply Highrollers onto my 729s 
I've gone from flows to arch's. Tyres seat just as well, I can't detect any squirming and they feel just as stiff to me (so far).
Only a suggestion.
I remember roger musson telling me that he considered 355s to be strong enough for a 15st rider on pretty rough trails. But narrow though (I've had some of those too!).