Nothing wrong with the way he "reviews" speakers. He has an opinion, he compares to other speakers etc...
He qualifies his reviews with, "in my room", "in my opinion" etc.... Nothing wrong with that at all.
No longer any upscale finishes. Don't care where he came from, doesn't change anything. Not a fan. Everything is off the shelf. You or I could build an identical sub. Not so with JTR, Funk, Harbottle etc...
Your best option would be another Rythmik F12.
Better yet if you have the budget and time to wait would be a pair of these -https://www.harbottleaudio.com/cassini-tradition/112t
or https://www.harbottleaudio.com/cassini-tradition/115t. Of Funk audio which work with Harbottle.
As for PSA-...
I have one for around 3 years or so. Bought on sale for around $125 at the time. It's been rock solid. Remote quit after a little over a year (out of warranty) Yamaha sent me a new one for free with shipping included. Paired with NHT SuperOnes version II and a Polk DSW 440 pro in my MBR. Perfect...
I'd go for the Kefs based on my experience with their entry level Q750s in a small room. The near perfect off axis response in both horizontal and vertical create a very large sound stage (in my room) 13x14x9. Walls and ceiling are painted drywall and the floor has a fairly thick carpet.
Different customer. Small, "life style" subs are what they are. And many customers like to have the same brand for all their speakers for whatever their reasons are.
Your 15" driver likely had a crossover at or below 200hz. I'd be surprised if it were even that high. Maybe check to see what the crossover was/is to be sure if it's in the area where you are now having issues.
Hardly.
If you want loud go get some JBLs, passive of active, JTR, or RTJ etc....
It's one of the best speakers you can get in its class for its intended use.