It is quite noticeable when switched on and off in Al's setup at CJ. I am not a fan of it at all. I personally found it rounded the edges off stuff for me but I would not describe it as euphonic. The fact that they admit it's not the most correct thing to do may have predisposed me though so who knows. I am certainly not in any position to come out against DSP.
I have one theory that people are so caught up in the live experience they fail to notice fact that it's not as smooth or alive or etc as they think. When you're in the room with an orchestra you don't really mind the etch on some stuff, but then if you listen to an exact (or very close) reproduction you notice all sorts of stuff. It's like watching a movie for the 1st time vs the 15th. I personally have no problem overlooking these things in a recording but they drive a lot of people nuts. Just a theory YMMV