Yes check on the spacing. When we used the 80/20 back in 2001 for our robot we had to check them every so often because they loved to slide on us. Also be careful with the 2 wheel drive robot, especially if you get into a pushing match with a team since yours could possible spin easier than one that is 4 wheel.
Also there I haven't searched through the White Papers on drive trains or other mechanisms lately so I'm not completely up to date on what they have. But i do know that if you are interested in researching drive trains there are a few helpful pieces that JVN wrote up on our teams website. One of them is here:
http://team229.org/resources/single/181
Good luck to you guys in the up coming season. Hope to see you guys doing well at the regional(s) you attend. Remember to K.I.S.S. and you guys will do fine.