I like that it's there to use, if you have a sound you're trying to get for a particular part, like a lead part or a rhythm part, when you dial in the rig for the tone and shoot the capture it's at first kind of in the middle of both tones, rhythm and lead.
if you want the lead tone only and only play the lead register when refining, the end result is a lot closer to what you want. if you want the rhythm tone only and only play rhythm when refining it's a lot closer to the rhythm tone. if you try to play both rhythm and lead when refining it kind of either splits the difference or just uses the last register it heard.