I'm 10lbs heavier and the superlight FM936 has held up well for me.

Did a race in NC with similar characteristics as you mentioned, 8 mile climb in the middle plus to more extended climbs, some rough longer downhill, the last - Mid Black was really eroded out and I was a bit outside my comfort zone there (particularly with my brakes fading by that point), but the dropper & slack geo kept me upright.

The enduro guys killed me on a couple of the gnarlier descents, but having a 22lb bike on the climbs meant I was long gone before they got there.  ;-) 

The Transition Spur is a single pivot frame as well right, but with a little more travel?

If I was buying now I'd probably opt for the FM909, mainly because I could go large and still get a 125-150 dropper in it.  The seat tube on the FM936 was a bit too long for me to go large.  2 water bottle mounts in the front triangle would be a plus for me as well.

Are you talking about Pisgah area in NC?

Good point on the single pivot Spur - I didn't realize that! I looked at the FM909 but wanted a 120mm frame - 936 seems to allow.

I hate buzzwords, but it's what I'm looking for. Ideally 120mm frame for a lightweight build as this will be a dedicated high mountain bike for long climbs. However I want to be able to descend the roughest terrain (but of course not at the speed of a true enduro bike). Planning on running a Fox 34 Stepcast in 120mm. Would like 66* HA.

Something in the realm of a Transition Spur or Santa Cruz Tallboy. I've been eying the Carbonda fm936, but I just don't trust the single pivot design for the rugged downhills - it just seems too fragile of a system.