Great choice in equipment. I too went from a RT-N66U to Ubiquiti Unifi. I was having unreliable wifi and after switching, I have never had a single problem in the 200 days I've had it.
I went with a single AP-AC-LR (mounted on 2nd floor) covering my entire lot including separate garage. Paired with the Unifi Gateway, but using a Netgear switch, no cloud key, just running it on my pc that always runs.
Found setup no easier or difficult than a typical consumer router.
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