I can't speak to Amplifi as I've just heard about it a few moments ago, but I second the UniFi AC Pros. Long story short, the 2.4ghz spectrum where I live is saturated, and the 5ghz spectrum is wide open. 2 APs, a Cloud Key, and a PoE switch later and I have full 5ghz coverage on both floors. I can bury the capacity with file transfers, BitTorrent, Netflix, etc and it doesn't skip a beat.
The bad news is if you're used to the cost of consumer gear, this ain't it. When it was all said and done it set me back $400. Throw in the cost of a pfSense router (because my old workhorse died recently) and we're at about $600. So, much like everything else, getting to that first 90% is cheap. That last 10%, not so much.
