Big Ubiquiti fan here......Unifi AC LR models.
Re: Roaming.....expectations of that, and how it actually works, and what supports it well....there's a lot of misinformation there.
Setup a bunch of Ubiquiti APs on the same controller, same SSID, different channels...and you'll find taking a laptop and moving about the office (or house) works just fine. The very very brief disconnect/reconnect the wireless client does as it changes from AP to AP is usually not even noticable.
Having true roaming, which Ubiquiti calls Zero Handoff, makes all of the APs appear as 1x massive AP. Same SSID and channel.
However....properly working with that also depends on the client....having drivers, wireless NIC software/manager, that properly supports that. Else....you'll find out it doesn't do what you hoped for it to do.
Ubiquiti has had Zero Handoff as a feature since controller version 3.1 or something like that...for quite a while.