Do you think you need a subwoofer?

The reasons for a sub with monitors is obvious. More and better bass, when they are integrated properly.

For "full range speakers" which only start to roll off at 32hz or below, unless you want to hear airplances taking off in home theater applications, or are an organ nut, I believe that the best use of a sub is when your full range systems create bass problems in your room because the location of the main speakers creates very uneven bass response. You can roll off the bass at a ligher level and put the sub in a location that doesn't exacerbate the problems inherent in the room size.

The problem with using a sub with any "fast speaker" is proper integration. This is especially so for speakers with little inherrent bass, say those that are down 3 db at 60 to 100 hz. This requires a sub that is equally fast in the overlapping frequencies. Very hard to find, especially with panels and electrostats.

Life is a trade off. :-)

Eldartford, I disagree with you a bit on the slow issue, only because I suspect that those folks who raise the issue are using the subwoofer in the mid and upper-range of bass frequencies, probably with poorly designed or shallow sloped cross-overs so you have a 15" cone producing the same sound at the same level as an electrostat, panel, of small mid-range drivers (as in mini monitors), the end result of which is likely to be a muddy upper bass and perhaps even lower mid-range.

I would agree that using a sub to fill in the bottom octave or so of a full range speaker system, using a cross over with sharp slopes, should cause no problem whatsoever, in fact it would be ideal. Optimally the full ranges speakers bass would not need to be attenuated at all - the cross over would only roll off the subs top end.

At least that has been my experience..........