I've also seen this kind of counter, but with back rolls instead of breakfalls. Uke rolls because nage doesn't keep uke's elbow vertical, then comes up out of the roll and counters with their own kotegaeshi. Just a couple of weeks ago, one of my sempai did this to me when he busted me doing a sloppy kotegaeshi. One of the more surprising reversals I've encountered...
Yeah, I've seen it with back rolls but haven't tried it. Appears harder to hold onto nage. Of course the issue with the other way is nage has to enter his escape prior to uke landing, so timing is very critical. Either way, I'd still rather just kick 'em in the back of the head on the way over, and roll back up. he-he-he! What fun we have, huh?!
Train hard, Play hard, live easy.
Dan P. - Mongo