The two π tower has a small footprint, low cost and deep extended bass. It is a smooth sounding speaker that is popular with just about everyone. It really has no downside and doesn't cost much. It is extremely tube friendly too. This speaker probably offers the most bang for the buck in the line, mostly because it costs so little and just sounds really good.

The three π speaker is the entry level uniform directivity model. It offers better room coverage and better dynamic range than the one π or two π models can. It really is in an entirely different league, putting you closer to a "price no object" class of sound system. You can build a pair of three π loudspeakers today and be quite happy, then a few months down the road build a couple of subs to go with them. This is the kind of sound system that is hard to beat, providing powerful smooth bass and uniform coverage throughout the room.

In the room you're talking about, I'd probably go for the two π towers. That's mostly because the footprint is important in a room this size. It would be great to get some larger speakers in there and also some subs, but you just don't have the room. Then again, you don't need a real wide sweet spot either, so the two π towers work nicely.

If you want speakers for a larger living room or home theater, that's when you want to check out three π speakers and multi-subs. You could also go with four π or cornerhorns, if your room will work with them. These offer constant directivity, and that, combined with multi-subs, provide a uniform reverberent field and a very large sweet spot.