Yes. I have a bunch of their 18's. They are good drivers. Some of their lines would not be suited for home audio though. The ones that would be good for HT are the XXX, MX and SX series. Unless you can find a deal there are comparable products for less though. Except for the XXX which is really expensive but is sort of unique in what it does. The MX's are nice too but again aren't cheap.
I have the XXX subwoofers and they have very good SQ with low distortion. They do not extend as well into the upper bass above 100hz as some other lighter drivers, so they are truly SUBwoofers and not woofers. I've heard that the MX line is comparable to the XXX in SQ but is just not as rugged and powerful in the deep bass.
Soundsplinter has very good SQ from what I've heard people say, but I've only heard one set-up of a 15" RLP and it was in a car so I'm not an expert on their SQ. Most everything that I've heard has been good though.
I'm looking for the best 15" subwoofer for the money. My budget for the driver is $300. I plan on doing a sealed box. Any recommendations? I listen to music and movies 50/50. I have a 600 watt amp to drive the subwoofer at 4 ohms.
Well the RLP is going to be better than the RE SX15 which would be RE's driver in that price range. You might be able to find an MX15 for $300 used, but that's about it and it would need more than 600w to really shine.
I'm going to recommend the CSS SDX15. I have 2 of them sealed. They are the drivers in the back in my avatar pic. They are $280 and are a very nicely built driver. the RLP15d2 would be nice also.