Man, those RFL's are BRUTES!! Talk about purpose built for power, yikes... It's not that they're bad, they look quite effective and I've seen them mentioned in SPL competitions. But do they have potential for SQ? Let me take a look...
...I'm all over MTX's website, but I can't seem to find the Thiel-Small parameters on those suckers to evaluate how they could work in various configurations. All their data sheet has is pre-digested specs on boxes they've already designed, and designed for POWAH!
Unfortunately, looking at the frequency response and box sizes, I can take a pretty good guess as to what those speakers would need, and it's bad news. From the looks of it, they like BIG boxes. I mean really big. Do you have room for two 6.5 cubic foot boxes? You'd probably need even bigger than that. The smaller you go, the less low frequency you get. That coffin-sized box will get you a -3dB cutoff at around 40Hz, which is the same as an SAS Bazooka. Of course, the difference is, the Bazooka can't take even a fraction of the power, but it IS a fraction the size.
Have you considered selling them on Ebay? You can sell them for a lot more unused "New In Box" than you can used. It's worth considering if they don't fit what you want, because they look like they're expensive.
...It's really hard to say without knowing what you want. Some people want the tightest bass possible, and for others it's all about how low it can go. That depends on the music you listen to, and how loud. What is it you're looking for?