Thanks for the replies, there is certainly some truth to the statement about not being as aero on a mountain bike, I run fairly wide bars and do not want to chop them down as I still use it for a lot of mountain biking. The wheel/tire combo I have works really well for road, they are conti sport contacts (26x1.3) with some lighter weight wheels. Running out of gear is a major problem since after 26/27mph I am spinning uncomfortably fast and now that I think back about the 200k, I missed a turn and me and another rider were riding close to that to try and catch the group again.
I think I may end up giving in, at the very least I guess it would keep me from having to swap tires all the time.