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.