I bought the Wild Think backpack. It's made to hold a Double Bull blind and all your gear. Anyone thats ever packed a blind any distance knows what a pain it can be. Add an xbow in there and it's double miserable. The pack takes the pain out of it. The straps and internal frame make the weight go away. The pack was designed to hold a compound bow but I take my xbow and put the stirrup in the pocket and use the strap to hold the stock and it works out really well. Pus the wide part of the xbow at your hips where you can turn it and not get caught on everything.
More here http://www.blacks-creek.com/doublebull.php
Watch the video on the page and you'll see what thought went into this pack. Quality is very high too.