Timely question for me!

One kid, another on the way, and the wife says I need to downsize my system (and not spend a ton on its replacement) so we can actually make use of the trunk from time to time.
She's probably right.
So the two 12s will have to go. Like 99Cat, I'm accepting the fact that I'm not going to get window-rattling bass out of a bazooka tube. I'd just like a round sound. I was looking at the nitrous bottle-looking tubes they have now (e.g.,
here though there are better prices out there) for giggles. I do have an amp that could work well with one of these (240W RMS mono, though with 0.2% THD), so it would be a nice match. Admittedly, I'm a sucker for the fact that they come in purple.
But are these horrible? Would I be better suited finding, say, a 250W RMS 4 ohm 10" or 12" sub (and if so, any recommendations)?
I'll miss the 12s for sure, but in about 18 months, when my cougar no longer has to be a daily-driver...then I can do with it what I want. As it is now, I drive 50 miles round trip daily and spend too much time in the car not to have decent sound from my stereo.