Bruno. Generally speaking, what sounds best in a speaker to most people is one with a flat frequency response across the spectrum. If you look at the M80s, they are +-3db from 36Hz to 22kHz and if you look more closely, they are actually +-2db from about 150Hz to 22kHz. The latter means that you get very accurate (much better than average) reproduction of sound through the mids and highs.
To add to what I posted about the mids on audioholics, I have found the reproduction of acoustic guitar to be exceptional on the M80s. Clapton's Unplugged is a very well recorded disc and the guitar is just incredible when played on the M80s.
As to soundstage, properly set up (as I listened to them at Axiom) the M80 system will give you an incredibly enveloping experience. Probably a little better than the Klipsch. Horns tend to have a narrower dispersion of sound leading to more off axis dropoff. I believe that gives you a smaller sweet spot.
Subs are more difficult. There have been a lot of advances in this area over the last few years that have really re-defined the top end and made this the most competitive area of HT.
Unfortunately, it is rather costly to bring a sub in from someone like HSU because you have to deal with cross border shipping and duties. You can probably add $200 to the sub for shipping and duties. I ended up going with the EP350 and its great for music. If it went down into the low 20s I think it would be a hands down winner in its category.
From what others have posted here, for subs like the SVS PB12nsd you trade off accuracy (music) for rumble/thump (movies). Mine is a music first system so that was the clincher for me.
As I suggested on audioholics, audition the M80s, and if you like what you hear, arrange to compare them to the Klipsch in home.
good luck in your search
