Thanks for the input. One thing I like about this forum is I usually get a lot of intelligent responses instead of "get Boss subs" or something like that.
I wasn't too sure with the RE either, based on the lack of technical data. I had to e-mail them just to get the frequency response, which they said 20 - 200 Hz, which I'm not too sure about as well.
I have seen some Boston Acoustic G5's popping up on Ebay too, and most of the Boston subs (G2 and G3) have a Qts above 0.6. The G215-44 15" DVC is going for $70 new on Ebay. I'd jump on that, but I have a wife and kids, so I have to behave somewhat. lol
I've been leaning toward the Infinity subs, as they seem to offer the best performance for the money. The JBL GTO-1214D (Harman yet again) has similar specs and price to the Infinities.
After having a JL Audio W3 at one time and knowing its sound and capabilities, I'm a little hesitant the Harmans won't perform as well, being disappointed and stuck with it.