Using those locations is fine. You will end up with slightly less ski pressure, as it lowers the rails about .5". It also changes the weight transfer slightly, as it lessens the angle of the front arm, making it softer under acceleration. Lastly, it makes the front shock slightly more progressive (less digressive is a more accurate way to describe it), making it a little firmer towards the end of travel. Since the changes are pretty minor, I would be suprised if you notice a difference at all. The 02-03 Pro Xs shipped with front arm using those holes, and suggested the front location for tracks with lots of cornering., The IQ turns fine...I used the rear location the last 2 years without issue.
Neil