I am 6'4", about 235lbs. I've put about 250 miles on my ST2S commuting to work. I ride paved roads and bike lanes all the way. Some paths I have options to take nicely groomed gravel paths that have some embedded rocks about the size of half a kiwi. I tried it once. Learned my lesson. It's way too rough. I ride with padded mountain bike shorts. I've also got a BodyFloat (which is amazing), and even replaced the Fizik saddle with something with gel. Even with all of these "buffers", the time on the gravel paths I have experienced are too strongly felt on the behind and back. For me, riding the ST2S on such reasonably groomed off-road conditions is not worth the discomfort. This is just my experience. YMMV. Alternatively, the ST2 with fatter tires may be better suited for more off-road riding as you describe.