Subwoofers?

I agree with Plato. I don't know your sub, however, I have mated ML with a genesis sub. It may be that to get an optimum mix there are four things you should try. 1. Lower the crossover point. 2. Check to see if the crossover slope can be changed to something like 24 db or even faster 48 db. 3. Change the location to right between the speakers and slightly forward or in a corner behind one of the speakers. 4. Finally have you tried bass traps?

Get the Stadium and stop worrying. It's just so much more musical, and still has astonishing output capability. Avoid the temptation to buy the Storm, it's not nearly as good.

And contrary to the above:

(1) Bass "speed" is indeed an issue, and is indeed difficult to achieve with very large drivers without getting very expensive (as in, many times the cost of the driver used in the Paradigm). I'm not disagreeing with the theoretical statement that bass is slow compared to higher frequencies, merely stating that in the real world, good-sounding 15" drivers are VERY expensive.

Technical diversion: You always have to think about these issues from the perspective of TIME. Just as an example, if a midrange driver has a 1 degree phase lag on a 1 kHz pulse (due to inertia), that is a delay of about 0.04 seconds. If a subwoofer has the same degree of phase lag, the delay at 30 Hz is 1.25 seconds! It suddenly becomes clear why the bass driver must be so good if it is not to sound "slow" compared to the rest of the system.

(2) A properly set up sub/sat system will almost always be superior to an equivalent full-range system, simply because it is almost impossible to set up a single box in a location which optimizes both imaging and bass response. It's more difficult to get the sub/sat right, but when you do, it's amazing.

(3) It is quite easy to design a good sub amp as long as it's not required to sound perfect in the mids and highs. The main requirement is a really big power supply, and this is obtainable quite easily. This is the other big advantage of the RELs: the signal to the sats never passes through the sub's circuitry, so it can't possibly get screwed up.

I recently posted a question here (and on AudioAsylum) looking for recommendations on a tight, fast, musical 15" subwoofer for 2-channel music only in a fairly large room. The majority of responses from both threads were for the Paradigm Servo-15.

Theo, rotating the sub can have a profound effect since the enclosure is around 22" long. In fact, in my system, I had the sub facing the wall (at mid-wall) and I had a standing wave that just wouldn't be tamed. But I rotated the sub so that the woofer faced out into the room, which effectively brought the driver another 22" away from the wall and now that big peak has been largely tamed. And facing it to the side instead of straight ahead has a large effect too, so you may have a couple of options left before you think about moving to a more expensive sub. I think it also helped mine when I put it up on 3 BDR cones, and by all means use that level control too.

The RELs have been getting great press, but even the RELs are subject to the same laws of physics that ultimately determine the performance of any and all subwoofers in a given room. So my advice stands.

That said, if you are very limited as to where the sub can be placed it may not be possible to achieve good results in your room with any subwoofer. Try the positioning and let me know if that works for you.

The room has a larger impact on bass transient response than the drivers.
If there's a large peak in the bass response of your room, the bass transient response is going to be slow and boomy, regardless of the quality of your subwoofer.

Bass traps are the only real solution to "slow bass" in most rooms; it is not possible to have too much bass trapping.
Parametric equalization can also be used, but this only compensates for amplitude, and does nothing to fix the room resonances that cause the amplitude problems in the first place, and attempting to equalize a large null can increase distortion and reduce amplifier headroom.

After fixing the room, distortion and doubling from the subwoofer itself become the next important issues to address, and on this point, high-end subs will begin to dramatically outperform low-end subs.

ie: the sonic differences between subwoofers are almost always swamped by the much larger effects of room acoustics and standing waves.
It's a small rainstorm within a hurricane.