You bring up a good point....I'm not sure for this degree of change that a base grind would be necessary and look for others input on this. I had no problem changing my skis and there was a noticeable difference of edge hold going from 1 to 1/2.
What I do know is that once you make a change on the base, you really shouldn't have to put a file to that base all season unless the edge got really buggered up. After you get the base filed to the preferred degree, all it should need for touch ups is a wet diamond stone. This way you don't take off to much base edge.
G