no, all madison stations are still going to be on the smae frequencies, and your digital converter will notice no changes. I will probably do it a few times to see if I receive any new signals from nearby markets, it can't hurt.
I tried an analog tuner last night and confirmed the 'nightlight' stations right now are 3 and 57, not 27 and 57 as your front page notes say. 15 and 27 are off the air and 21 and 47 are still on.