I agree w/ both Sonance and Ghunter.
A quality true full range speaker will be better for music than a poorly setup speakers + sub combination. However, if you're looking at subwoofers such as Velodyne's Digital Drive series, Revel B15, Ultima30, Rel Stadium, etc..., you'll see that a well placed and executed subwoofer will work as well and in most cases, better than a "full range" speakers w/o a sub.
For example, Totem Hawk + Velodyne DD12 combination will produce a very flat frequency responce from below 20Hz to 20kHz. I highly doubt you can find a true full range speakers (Wind goes down to 24Hz supposedly) that can do the same for the same price.
The important question to ask is, do you really need a truly full range (20Hz-20kHz) sound? If the answer is yes and you love the LFE on movie tracks, I think a subwoofer will make a huuuge difference in the experience and more than worth the investment.
It all comes down to personal preferences and needs, but w/ today's quality subwoofers, we really don't need to worry too much about the integration with main speakers. The subwoofer matching technology has come a long way and I believe they've gotten it right now.
Sorry to stray off the topic a bit, but for me, if I had the money, I'd add a quality subwoofer even if I had the Totem Wind loudspeakers.