Just tune power levels and RSSI settings. Everything else I pretty much leave alone and let the virtual controller handle.

"I" devices are the worst clients by far. I usually set RSSI between -80/-75, seems to do the trick for them.

I have one particular site that receives zero cellular service from any carrier. The customers all use their cell phones wifi calling to talk to customers. If handoffs weren't working properly, I'd certainly here it from these people.

When I find "I" devices being sticky in a certain area, its usually the outskirts of the system. If client wants better quality in that area, another ap goes in.

Same client from above, they have an outdoor patio (basically the roof top from the floor below them). This area wasn't part of the initial design for wifi but still received "OK" signal. But this area was right where an overlap occurred and would sometimes stick to the weaker ap. Slapped an outdoor ap out there and problem went away.

There is only so much that you can do with stubborn devices.