speakers with subwoofer-style base drivers

I wonder if anyone out there has comments about subwoofer-based speakers (that is, small cabinet with downward-firing drivers) vs. the other approach (big enclosure pushing air forward) for music playback (ie NOT home theater).

I have new speakers with each speaker relying on it's own small cabinet with down-firing driver to produce anything below 250Hz (the rest is handled by electrostatic panels). I have not had this kind of speaker before. I know that all rooms have resonance behaviors that place a load on the bass drivers no matter how they are designed, but I seem to be having a more difficult time than I ever remember before getting even decent bass.

It seems that no matter where I place these speakers, I have severe bass nulling in the middle of the room. Along the walls, the sound is good, but move more than 2 ft from the wall and the bass just goes away, which really messes up the overall sound of this hybrid design.

Unfortunately, all the spouse-negotiated listening options are away from the walls. Another problem is that I don't get much bass "slam", but I do get deep bass when the note is sustained. So it SOUNDS like deep bass (house rattles), but it doesn't have any impact at first, only after it builds up. For example, with a drum hit, you can hear the sharp rap of the initial impact, but the bass note comes up later than it should. Just doesn't sound natural. Just a rap and a boom, no thump.

My sense is that the subwoofer approach relies on coupling with the house's construction and maybe it works best in a rectangular room. I have an open floor-plan house (ie, no rooms dividers) with a slanting roof and sort of an odd shape (imagine a room about 100 feet long and 15-20 ft wide wrapped into a fat letter G shape with beveled corners). I don't think I have any square angles in my house at all.

So I'm wondering if I will be able to get a subwoofer approach to work at all. And if subwoofers need to get a resonance going before you can hear the note, I wonder if the subwoofer approach can ever deliver "slam", or is it mostly good for sustained notes?

I hate the thought of it, but I wonder if I should switch to speakers with big ol' cabinets that aren't so dependent on coupling with the room.

Any comments / experience with this type of challenge?

Consider solutions like Genesis Technologies G5.2. Waist high floor standing cabinet, and quite narrow. All down firing subwoofer assemblies will eventually sag. Each G5.2 has its own built-in subwoofer with its own amp all built into the one cabinet. Very spouse friendly and forgiving in many room setups. Mids and highs rival the best electrostats. Best wishes in your quest.
I have speakers with subs intergraded and work grate. There should be a way to adjust bass on them. It sounds like your issue is more room acoustics than anything else. Yes it is normal if you are near a wall you will get more bass. Also if your speakers are near a wall 3' or other object it will effect the bass and amplify it especially the low end. You may also want to make sure your speakers are spiked on a nice solid surface like granet blocks if they are not isolated from the floor you will get mushy bass. The lack of square angles is actually a help corners are usually a issue but it does complicate set up and positioning. I would try to get the dealer that sold them to you in there to help with the set up or maybe a friend that knows a lot about acoustics and can bring a sound meter and do some level measurements.
A buddy of mine has the same problem (insanely large room).
To get any bass at all he has to use a separate subwoofer that has REALLY high output.
Audition a big sub.
If you are on a budget the Martin Logan Descent may fill in.
If cost is no object there are any number of high output subs.
VSA has a new one called the VR-S/7.

One design that I like very much is that of the NHT 3.3 (two pair are selling here on A-gon).
These speakers use side-firing woofers that face inward. The speakers are so deep that they create their own wall. In fact the 3.3 is suppsed to be placed against the wall. I have the 2.5i's (baby brother to the 3.3) in a square room. Because the speakers create their own walls they make the room sound more like a rectangular room. I have not seen new speakers that use this design but I'm sure someone is doing it.

Good luck!