I’ve got an R3 at home which generally works well. Flashing mainline OpenWRT was pretty smooth and easy. It’s been a while since I did the bring up, but I do remember having to jump through some hoops to get a partition layout that would utilize the onboard storage properly. By default it only left 10mb to install additional packages which seemed to defeat the purpose of having all of that emmc available. That may have changed in the more recent releases.
One bug I encounter regularly is that some (maybe older?) Apple devices seem to be able to lock up the router. Adding watchcat can get the thing rebooted in less than a minute in the event that it does hang, which makes it barely noticeable, but it’s not an ideal fix.
Depending on the devices you have in your house that might be a showstopper or of no consequence at all. Otherwise WiFi speeds and signal are great, as are general performance and reliability except for that bug I mentioned. Haven’t used VLANs but it’s all there and the flexibility of OpenWRT is great.