Most the people I ride with have compacts and we ride in a pretty flat part of the country. I've made several observations. First, they are usually riding in or near the big-big or small-small combinations. It seems that "cruising speed" for us is at the high end of the little ring or the low end of the big. The other thing I've noticed is that riders with compact cranks seem to use only the big chainring. They'll stay in the big the whole ride, using the 6 or 7 largest cogs. I don't think some of them even know they have a small chainring - a friend recently asked for me to (constructively) criticize her riding. I said "I don't think you know you have two front chainrings." Later on she told me that that hurt, because "I know it's true."