I'll diverge as well. I had the R7000 and it served me well for 4 years, but then started having reliability issues (I'm guessing heat related; maybe the thermal paste drying out). I've had gigabit internet the entire time and it was able to handle the load no problem.
Last year I really started to get into home automation/smart home type stuff, and I don't know if it was the beginnings of age/heat having an effect or if the first-generation hardware didn't like it, but once I started to get a lot of devices on Wi-Fi, it just wasn't quite as stable or reliable.
I looked hard at Ubiquiti, and the idea of full control and specialized/dedicated hardware really appeals to me. But, I had a hard time with the costs (CloudKey, UAG, PoE switch, probably 2 nano APs, it was over $500 for everything).
I decided to take a chance (fully expecting to return it) and got a 3-pack Google WiFi set for $195 (and I've seen it for less since). In short, I'm surprisingly happy with it, and have no regrets. No, it can't do everything that the UBNT setup can, and I don't have full control over everything, but:
+ It's able to handle 45+ devices simultaneously with no issues
+ I love the real-time and historical network metrics -- it's awesome to have this info available
+ It's really easy to label devices on your network so you know exactly what everything is
+ Guest network is easy to setup and control, and you can easily share items from the internal network (ie printers) to the Guest network
+ Cloud control is great, and I can easily view and configure my network from anywhere
+ I first just installed one puck, and I had a strong signal through my whole house, whereas the R7000 (known to have excellent WiFi strength) struggled to deliver a good signal in one area. That said, I didn't have any other devices on the network at the time, and I paid for 3, so I (likely unnecessarily) installed all 3
+ Very stable and reliable
+ Strong WiFi signals
+ Able to define my own DHCP reservations & DNS servers
+ Able to use the spare port on the puck to create a wireless bridge very easily (plug and play)
+ Very easy to setup and configure
- The app reports that I average about 650MB down and 250MB up in its own built-in internet speed tests, whereas I usually had 900+ both ways with the R7000, but in real-world usage I can't tell any difference at all (Steam still downloads stuff at the same speed as under the R7000), and I'm able to run multiple HD/4k streams with no issues. Since I can't tell the difference, the numbers don't matter to me.
- Each puck only has 2 ethernet ports, so I picked up a couple of 8-port switches to give myself more wired connections. These were quasi-managed and somewhat smart, and only ~$20-25 each, so no big deal.
- Wish I could create more detailed sharing rules or create some additional VLANs, but this is minor. UBNT would have allowed this, but would be more difficult to configure and cost at least 2.5x as much.
The Google WiFi doesn't have great specs on paper, but in practice it works very well. You could probably find a single unit on sale for around $100, and that might be enough for your whole home (based upon the 1500 ft2 you mentioned, although with 2 stories and a basement you might need more). Plus, you can add more easily if needed. If you think you might need 2, get the 3 pack, as it's the same price as buying two individuals (if purchased on sale).
TLDR: Try the Google WiFi. If too expensive, go for the R7000.