I wouldn't go to larger cranks either. You're dilemma with this bike rings a bell with me... I like my current rig but as it's happened before over the years I came across a new Trek Domane in a bike ship not long ago and was pretty interested in it as coming across large bikes sort of turns bike-buying into a treasure hunt and is especially fun if you can get a good deal on something you really like. This one was a size 62 which is unusual since 61 is usually tops and, I think it's be perfect for me and maybe you too but I passed on it because the seat post arrangement -- like what you have -- it sort of scared me off because, If I'd bought I'd have wanted 165 cranks and I wasn't sure how high the seat could be raised... especially being CF. I may be stuck with my alloy frame and an alloy seat post that'll go far higher than I'll ever need.