Jon:
You couldn't have selected two better bows to choose from, I have owned both. Might I suggest you reconsider the length if you are drawing 28" especially with the Hill, I would not go any shorter than 66" and probably 68", personally I shoot the 66" with a 27" draw. The main difference between the two will be limb style. The Hill will be narrower and thicker, where as the Liberty will be thinner and wider and a little more backset. I think the Liberty will have a little longer riser making the working part of the limb shorter.
Bob