Its all personal preference, if I compare a tower and a bookshelf from the same series with the same drivers, to me the bookshelf more often than not sounds better, but the tower of course digs deeper, smaller enclosures mean less resonance, and tend to have a tighter all around sound... I also like A LOT of bass, I like a strong lower end, that a 6.5" driver isn't going to pull off, and I like it a little louder than it may have been recorded compared to the mids and highs so this brings a whole new problem to the equation when trying to "balance" a system to your liking...
In my systems I almost always cross to a pair of subs, in HT 1 sub is fine but in music I like 2, 2 seem to blend in effortlessly where a single sub will sometimes be instantly noticeable in a music system... So if you do it rite, pick a pair of fast musical subs {usually small sealed units will do the job}, cross low enough so you NEVER get voice through your subs, make sure your mains are relatively close to the subs so you don't roll off a bunch of content {you don't want to cross the mains at 140 and the subs at 50, you will essentially lose all the material that falls in them lines..}, but you also don't want overlap... Then placement is another obstacle, I don't like stacking them since for some reason it tends to loose the smoothing effect of have dual subs, so I do one left and right obviously, and just move them around until you get it rite..
So after you find your crossing points and you get the placement perfect, you can balance the bass and main gain, this is where I appreciate the 2.2 systems, I can just turn the sub volume up a little to get that strong low end I enjoy...
So now, will it pay off? should be the next question, for example does a set of sierra 1's with a pair of sb1000's {cost $1825} sound as good as a set of sierra towers {$2000}, I have done this exact comparison, and YES, I prefer the books with the dual subs, once you get them dialed in, they play louder {obviously there is an additional 1440 peak watts there}, they sound clear as a bell {so did the towers though}, and the bookshelf/sub system easily took over the room vs the towers played and sounded great, but lacked the authority I was instantly addicted to from the subs... Its not a surprise that dual 12" subs with 300w amps have more quality and quantity than a pair of towers with 400w total between the two...
So in my opinion you can get more for your money when going with bookshelfs and subs, there are a few good sealed sub options out there, SVS SB1000 $950 for a pair, SVS sb12 nsd $1200 pair, HSU ULS15 $2200 a pair shipped... I have tried all 3, my wharfedale sw300's are a great sounding sealed sub too, but hard to find in the US... You don't need much subwoofer for a music system, for a 200wx2 set of mains, I bet you can get away with a pair of 150w 12" subs, but I've yet to hear the musical 150w sub that I would want in my system...
Anyway, find what you like, there are some very capable towers out there PSB T2's I heard a while back have a really nice bottom end, some of the b&w diamonds have a great low end, but out of all the speakers I have heard there aren't many that satisfy me when it comes to the bass...
