My wife and I rode MTR in Springfield IL this year. You are correct that people rode all speeds, distances and paces. Although central Illinois is fairly flat there were a few hills along the river that some teams walked and I was glad that we put our 11 -34 cassette on the tandem. From your description of your riding I am sure that you would do fine at MTR in 09. It is a great time meeting and visiting with people, there are workshops and interesting bicycling items in the vendor area. MTR 09 is in Rochester, Minn.
Sheldon