snapsc - My room is on the larger side of the size range for the 2000s, although I sit only 9' back. Without the subs, the 2000s seem to go well into the 30's, probably around 35Hz, with a good amount of output. (Sadly, with my amp in the repair shop, I am listening now without the Vandy subs, but only my HT sub, an old Def Tech PF15. Even through my cheap AVR, these speakers sound lovely!) But with your sub properly dialed in, you should have no bass issues.
Your guess on the need for larger Ohm Walsh models in bigger rooms is correct. The thing about this line of speakers is that the sound is very consistent model-to-model. You gain low-end extension, higher dB output and perhaps some better macro-dynaimcs as you move up in size. But timbre, resolution, soundstage characteristics, etc., are all about the same, whether you have the Micro-Walsh Tall or the 5000s.