Stefan, I'm in the probably the densest home environment possible and I'm not seeing the RF-Filtering issue you are talking about. I've got one B5 link shooting 2.7 miles over the top of hundreds of homes 15' above them running full-modulation with a 40MHz channel. It also includes going right past a tower with eight 5GHz radios and over the top of 2 Ubiquiti 5GHz Omni's. The story that Ubiquiti was selling with the AF5 doesn't seem to be the issue they tried to make it out to be. In addition, the AF5 doesn't even cover the entire 5GHz band. If you are willing to give up some spectrum, then you can add more filtering but not only is the Quantenna chipset pretty good at filtering, the ability to use all the spectrum to get around direct interference issues is far more important than the filtering story that Ubiquiti is putting forth.
For example, I have to manually set 3 channels on the AF5x whereas on the B5c, I log in and find it on different channels all the time because the interference is so bad. The customer never sees the issue though. Auto-Everything is the future for high-interference environments.