I've had a REL Storm III for years and no longer use it, the main reason being that the high level output from the amplifier speaker terminals is not compatible with a bridged amplifier. That's the explanation I was given but the result is a loud hum (not ground loop) from the REL whenever the amp is powered off, it doesn't hum when the REL is power cycled and the amp is powered on again

. I mention this as something to check out before buying one. It works fine using the low level RCA but it misses the benefit of integrating with the main speakers. When I had it connected to previous amps I owned it integrate very well in 2 channel music systems.
The Storm is too small for my room, it's really built for a UK sized living room - I only have knowledge of the ST series, and some of the bigger ones (such as the Studio) are probably better sized for larger US rooms.
I've seen great deals on Audiogon, but shipping costs must be significant.
I also found the REL more of a music sub, and bought an SVS to handle HT.
REL was started in the UK by Richard Lord, he sold out a few years ago to Sumiko - the US distributor. I had an amplifier fault and found Sumiko to be very customer unfriendly at the time, this may have changed.