My teams first year, we used 8020 for most of our robot... except for the main frame. We stuck with the kitbot frame, which is designed for a 6 wheel drop-center drive train. It's actually pretty easy to attach 8020 to the frame, too - you can add vertical members by simple tapping the hole that goes through the middle of the 8020. We're the robot on bottom in this picture:
http://www.chiefdelphi.com/media/photos/27516
It just goes to show how durable 8020 is... a puny little frame held up 2 robots... and one of them was on that thin little 8020 arm!