@blinkenlights
Using Unleashed and a master/slave setup everything just seems to sort itself.
I find I have better load balancing than I did with my dual Ubiquiti setup.
If I reboot the AP's for a firmware update or something. The unit that comes up first will end up with a heavier client load, but if I go back and check after a while, be it my devices or the AP and its management I find that I have a very even client load and every device is connected to the best AP.
Now I have one in the front of the house and one in the back so the signal strength for one AP should be better than the other for any given device, but when I was researching these devices they support "cluster mode" where you can literally put two ap's right next to each other (or more) and they are supposed to be intelligent enough to distribute the client load between them.
I am not sure however is that is a feature of the AP management (Zone Director) that is not part of Unleashed.
But, going back to a major point I had. I used Iperf to do life bandwidth testing between my Ubiquiti AP's and the Ruckus AP's using a laptop and cell phone and watched how the bandwidth degraded with distance (signal strength) and found having a technically slower AP with stronger signal resulted in better connection and bandwidth than a lower signal strength from a faster AP further away.
So I think having two cheaper AP's spaced out in an average home will be more beneficial than a single faster AP even if that one AP can easily reach all your devices. Additional benefits, equipment failure does not mean critical down, and rolling updates means no downtime to devices.
In summary I think two R720 would be better for just about anybody than a single R750 given similar pricing total, and in my case where I have no 2.5gb back-haul I also get better distribution of upstream traffic via standard 1gb connections assuming I do not need to break that 1gb speed barrier for any single device, and I hope not because that device should be hardwired with a 10gb NIC