That's one of the huge benefits of aerohive. The AP's balance load very well not only between AP's but also between the two frequency's 2.4GHz vs 5 GHz. So if there are too many client on 5GHz the AP it's associated with can push it to 2.4 if that is an option on the device. You can toggle that on or off in the configuration however for high capacity environments they recommend keeping it on to better balance the load. We have never had an issue with a device roaming inappropriately.