I'm leaving on a bike trip fairly soon, and I have a choice between two bicycles. One's a 21-speed mountain bike with Shimano shifters and eyelets (relevant for a national tour). Its downside is that it's too small for me -- the frame, that is. I have the seat jacked ludicrously high, but it works.
The other bike's a road bike that is my size, but needs a total rehaul. That is, it's in excellent condition, but I need to upgrade from its current 14-speed to a 21-100 inch gear range, replace its handlebars, try to fit 700x35c tires on it, and fasten false eyelets for a rear rack. I also need to move the shifters up from the (stem?) to the handlebars. It'll cost hundreds.
My question is, would I be as well off taking the bike with the smaller frame? Not even weighing in the costs of overhauling the road bike, does size make a difference in riding quality for long tours?