Those of you who have used the Bull Pac aluminum pack frame for packing out animals, what have your experiences been using this pack frame?

It is heavy and a little uncomfortable, but will carry large loads (larger than you can carry). A functional frame for hauling heavy loads over long distances, but there are far more comfortable packs out there that will carry as much (except they are much more expensive, about double or triple the price). A good product for the price.