I tend to think if someone thinks they want a USG, they should just stick to their ISP router. Really the only thing it does is make the Unifi controller report pretty things.
You can't do many "advanced" things with it in terms of routing & NAT rules. And as has been demonstrated a fair bit lately going by posts on here, doesn't actually give any better routing performance. Also, if you are want to do clever routing, you need to know how to configure it. And if you know how to configure it, you wouldn't buy a USG in the first place.
Then if you want to use the properly cool stuff like IPS, they are even more useless. I would really question the need for IPS in a home environment though, as you have to know how to configure it first. And if you know how to configure it, you wouldn't buy a USG in the first place.
I would liken most USG's in a house, to those Fortinet's/Junpier/Sonicwalls/Sophos' you see in a businesses that some IT houses just love installing. Just expensive routers, that aren't doing anything different to a $90 Mikrotik because the cool stuff isn't actually configured.
OP - I'm always on-board with going over-the-top in your home set up. Why not right? But do it properly, get the cool router, not the "easy" one. Just be prepared to learn.