For slow rockcrawling, I'd even argue that the 2.5's are even overkill. .
I wouldn't. I've found the boulder fields leading too and from a lot of rock crawling sites can be very taxing on the 2.0's. I've noticed that as the day gets later the body roll seems to increase. Could also be driver fatigue though. But I haven't ran 2.5's yet so I don't know how much difference that will make. I'm hoping its significant though.