That's good to hear.
I think the other thing about flat speakers though, or at least according to my experience with the Mackies, is that when they themselves are so flat and clean, you have a lot of leeway for error in the room. If a speaker starts out with a bump or resonance somewhere, I imagine it might not take much to push that bump into uncomfortable territory (if it isn't already). But I have never had my Mackies in treated rooms and they always sound a bit different (I've heard them in a lot of rooms...) but they always sound good, they never sound like they've got anything seriously wrong. Worst case, I tweak the acoustic space settings on the back a bit.
I thing it's the same with flat, clean headphones and different recordings/gear. With flat headphones you have more leeway for bad recordings or less than ideal gear.
