In terms of durability, there is reliability with high round counts, and durability when dropping the optic on large rocks. I am yet to break a single SRO, and have been using them as primary since they came out. I have dropped them, but not onto large rocks. I have broken more than a handful of RMR optics, type 1 and 2, and have a 2 on the way back from Trijicon right now.
Based on my experience, I think the SRO is tougher than a RMR over high round counts. I do think auto intensity works better on the RMR than the SRO.