I have the Furman ELITE-15 DMi. My power is really stable at house but I just wanted to have the peace of mind with protection in place. I been running this unit for years and its a solid piece of equipment. It’s only been tripped/shutdown twice. Once I came home and it was tripped so not sure what caused it. The other time I was having some work done on the house years ago and crew caused some kind of surge and it tripped. I have done multiple tests with my amp plugged into the wall and the Furman and I notice no degradation by going through the Elite - 15. I think you could purchase any modern Furman product used and if you are not satisfied , easily sell it for not much loss.
https://www.audiogon.com/listings/lisa2j3d-furman-elite-15-pfi-open-box-ac-conditioners
Several on EBAY as well
https://www.audiogon.com/listings/lisa2j3d-furman-elite-15-pfi-open-box-ac-conditioners
Several on EBAY as well