You can stick to 802.11r only by lowering the transmission power and have all the APs on the same channel, in my tests it ended up switching much faster than K/V. (~75ms) On iOS, equal channel with correct ESS will switch liberally. On Android 14+ with Broadcom chip it will start conservative, then switch liberally after the first poor signal switch-over event, up until disconnection. Android (Pixel/Moto) will never…
On my Unifi setup at home with multiple APs I had to disable 802.11r to get things to roam fast. I have Android and Linux laptop, wife has iPhone and MacBook. With 802.11r on, things would disconnect for 60+ seconds before reconnecting. It was a constant frustration of "arrrrrrrggghhhh fucking connect damnit I'm standing a meter in front of the AP can't you fucking see it fuck fuck fuck just connect, it's right THERE…
You're at the mercy of UniFi not having any show stopping bugs (haha), the client device supporting 802.11r or at least tolerating it, and the interaction between UniFi and the client not having any show stopping bugs.