same here, I have a 4500 sqft home and I use 3 Ubiquiti AC-Pros (one per floor) and I have excellent performance and coverage. In fact, in my case, two of the APs are on the same floor just that one of them is in my foyer area that is open to the upstairs and this covers the upstairs floors. And before I installed a 3rd one in my basement, I had good basement coverage there and now that I have added one to the basement, the hand offs work seamlessly. I checked and rechecked - I have roughly 15-20 wifi devices from TVs, tablets, phones, kids tablets, chrome cast, fire sticks, and probably some others I can't recall and all my devices appear localized to the nearest AP and roaming, typically with my phone and tablet, works pretty well.