I have a F350 with the factory '5th wheel prep kit'. The factory drills the holes in the bed and also adds an additional electrical plug-in inside the bed near the tailgate, making it real easy to plug in the fiver cord. I assume GM also has the prep kit option. You should absolutely get this. Why would you not ? If you don't then some other shop will be drilling the holes in the bed. Who would you rather have do this job ??
I have a MorRyde pin box and a BD3 hitch. I absolutely love this combo. The BD3 pretty much eliminates the up and down motion that goes on between the fiver and the truck and the pin box gets rid of all the chucking back and forth motion. I can look in my rear view mirror and watch the pinbox 'jiggling' which means it's absorbing all the little road bumps, etc. When you hit a major bump, the air bags in the hitch do their thing. And note that the air pressure is adjustible so you can get the ride you want. I really do not find any negatives with this setup.
You actually will have 3 components from Hensley if you get the BD3 for the factory prep kit. Their will be an adaptor that attaches into the bed 'pucks' and then the BD3 is in two pieces. It is not light because we're talking serious metal here but 1 person can take it apart and move it. Call Hensley for the individual component weights.
I full time (pulling a 14k GVW fiver) and have been using this system for 2 years now and am completely satisfied. I would not change to anything else.
I do know that the B&W hitch has a great reputation and many satisfied customers too.
Tim