So how many people are using subwoofers

The Aerial SW-12 sub nicely rounds out my nearly full-range Aerial Model 9s.  Filling out the bottom octave adds a bit of warmth, fullness and does make a difference wrt to depth and drive on certain music, IMO.  It is not just the frequency extension but the drive that a good sub can add because even speakers with specs extending into the lower registers are seldom able to provide the level of drive in those lower frequencies that is provided by a good sub.

One method that has worked for me in matching a sub with main speakers, is to initially set both the upper frequency and level of your sub(s) a little lower than you would think is needed, listen for a period of time (e.g, a week or more) and then listen without the sub.  If you miss how it sounds with the sub in the system, then you are probably on the right track.  You can always bump it up a bit and repeat, until you reach a point where the sub is interfering with the balance of your system, then you have gone too far.  I suspect many who don't like subs in their systems for music either have them turned up to high, either the frequency, the level, or both, or maybe have a sub that is too slow to mate well with their main speakers.  Placement can also be played with.  A corner placement has worked pretty well for me.  I would like to add a second SW-12 and I am curious to hear from anybody using the AudioKinesis Swarm sub array.

28,237 people are sub people.

If your goal is to hear it all kinda crazy not to. 

I have been running different bookshelf size mains with a sub for many years.  My room has a nasty peak at 40 Hz so it was always tough to get good sound with floorstanding speakers.   

My current system is a pair of Revel M106 speakers paired with a REL R305 sub.  I run the mains full range and drive the sub via a Velodyne SMS 1 which serves as the low pass crossover and allows me to tame the room mode.   The sub is crossed over low with a steep crossover, it'seems just the right amount of low frequency given the decent bass from my mains.

I'm driving the system with a Conrad Johnson Classic 2SE preamp and a pair of Quicksilver Mid Mono amps running KT66 power tubes.   My main source is a NAD M51 DAC fed by an OPPO 103d universal player.

For me a three piece system works best.  Friends and family are always impressed at the performance of such a small set of speakers. 

I'm using Golden Ear Triton One's. The sub is built in and can go to 16Hz. Sean, I think this qualifies as an exception in the case of vented. Dennisj, besides my T1s I know there are other high-end speaker manufacturers that use powered woofers of some kind. Not sure what you believe they are messing up but I do agree there can be an audible difference between a powered sub and non powered.