Consistancy if golden with a bow. If you've been shooting a lot with your quick nock, and have established good and comforatble form, then by all means, changing your draw length by 1/2" will throw your form out of whack! If you use a kisser or a peep sight, however, I would still think you could make it work, BUT will you be comfortable and consistant that way?
Did he make the string loop a long one. I always tie mine so they are very short, jst long enough for the caliper jaw to fit into, then they will stretch some over time!
A draw length that is too short is easier to shoot well compared to one that is too long!