Do add the KEF KC62 to your audition list. I think all KEF dealers would stock these.
If your listening room is not huge, it will do fine. I am very satisfied with mine.
I have used older RELs, a Martin Logan Dynamo previously. It may not match the older RELs’ musicality (by a small bit) but it goes very low, it’s fast, tight, integrates nicely and is easy to place. It’s also tiny by subwoofer standards.
I don’t have any experience with HT set up, but given how fast and responsive this sub is I think it will do well