We used them last year with the CIM motors for our drivetrain - NO problems. We originally planned to use 4 CIM/DeWalt assemblies (one per wheel) but had to drop to two to make weight and still had plenty of power and speed. We have already ordered our XRP drills to cannibalize for this year's bot (see my source info in
this post).
You should make sure you understand how much power you need and can effectively use. IMHO two CIMs per tranny is overkill, as possibly evidenced by the post you referenced (
"The transmission actually stripped the threads from the inside of the sprocket" ).