Boy am I glad I subscribe to the CD RSS feed
Perhaps I can elaborate. We are building a new cart to last us as long as FIRST lasts (forever). We've agreed on some sort of lifting mechanism (suggestions here are appreciated), and that it has to be narrow enough to go through a door, as well on the coach bus we plan on taking to nationals. As far as wheel base goes, I think working on a robot on a 4 caster setup will be bothersome. Unless they lock somehow. We were considering mounting a tool chest on it, but I don't have the most recent plans (I attended to beta test meeting rather than the cart meeting).
EDIT: And we want would prolly power it off a robot battery.
Personally, I think the biggest problem will be with the lift, and keeping the cart steady while it lifts. Our current cart does this, and it has almost tipped at least once (good thing our pit crew caught it)