I know, but I was giving an example of what we used last year, and what we plan to use again next year. We don't use the drills because we don't prefer them for drive (I'm not going to turn this into a Drill vs CIM thread, I'm just saying we prefer CIMs for our drive)
But yes, we had no problem with this system last year. If you wanted something basic, your idea would work fine. The motors didn't have much of a problem with the speed gap, as you said, programming fixed it fine.
Remember also that many rookies fall into the 2 wheel trap and put casters on the front, making turning very difficult.
For rookies reading this thread, make sure your casters follow behind your driving force. They weren't designed to lead.
2 wheel drive can be a very effective style too. It's also a good way to have a quick and easy drive right out of the kit.
But we're home schoolers, we don't live by the rules...
