I am frankly not a fan of high break falls. Step outside and do a high break fall on the pavement. Besides the obvious results of such an adventure, the high break fall keeps me from staying connected to the nage so that I can continue my attack.
I have done high breakfalls on hard surfaces without any "obvious" results (would I do a lot of breakfalls if we always trained on hard surfaces? no). Breaking away to do a high breakfall does not break contact more than breaking away to do a roll, actually most time less since I always want to maintain connection through the fall. Regardless if I´m being thrown with a koshinage, ippon seionage or hurled over the shoulder in a sanshou style double leg.