I own a REL strata and I'm very pleased with it. It is crossed at 30Hz with Spica Angelus in a 10x12 room. The soundstage has not collapsed and it is not a one-note thump. In fact it complements the spicas wonderfully. I only use it for 2ch music. I would not discount Doug's post, since REL didn't work for him, but I would balance it against the many happy REL customers.
I think a strata might not be powerful enough for HT, though, especially if you like to crack the plaster.
So RELs are very good and easy to resell (though somewhat overpriced in the US relative to the UK). The only other sub in the same price range which people seem to like is the ACI titan. You might want to home demo one of each, though personally I'd go for a used REL : it's a no risk policy. If you don't like it you sell it for the same as you paid yourself.
I think a strata might not be powerful enough for HT, though, especially if you like to crack the plaster.
So RELs are very good and easy to resell (though somewhat overpriced in the US relative to the UK). The only other sub in the same price range which people seem to like is the ACI titan. You might want to home demo one of each, though personally I'd go for a used REL : it's a no risk policy. If you don't like it you sell it for the same as you paid yourself.