Thanks for the review. I've read a lot of reviews about the UDM both prior to and post release. General consensus is that its still Alpha, and should have never left EA. Your review parrots the same...
I feel Ubiquiti has become a victim of its own success at this point. A lack of consensus on direction (look at their product stack!) with their products, and growing too fast has lead to some cracks showing.
The scary part is that there really isnt a comparable competitor. The AIO solutions from companies (like ASUS) leave a LOT to be desired. I dont think its much to ask for a prosumer grade product, that isnt junk or expandable (in a true networking sense) for the 300 bucks ASUS wants for a router today.
For APs, you could always look @ used Ruckus gear (just make sure it can run Unleashed) from eBay if you are ok w/ that. I'm extremely happy w/ my Ruckus R500. But for switches / gateways you are mostly right. Well besides PfSense for a gateway, but it scares people for some reason .