Ive heard the 2001 and played with the 603 and dont really find them noisey...i do find that when you get into condensers after dealing with dynamics(sm57), you have to get used to all the unwanted sounds the mic is picking up.....i dont consider this noise.....you just have to record in a quieter environment...in my case, the closet.....
this may not be what you are talking about, but its my only clue....