I'm guessing you already have the hitch in your '15, and it is the fiver that is being upgraded to a larger unit.
The Reese should be just fine at the rated load, and if it is already installed in your truck, I suggest you give it a try before dumping it. I'm not sure why some folks just never seem to trust their fifth wheel hitch. They never fail in use, but something about the size of these trailers compared to that little pin, gives folks the heebie jeebies. We trust truck ratings, but distrust hitch ratings. Why?
I don't think the hitch will be a problem, but you may wish you had some kind of air-ride hitch on a trailer of that size. Which might mean a new hitch, or new pin box. Still suggest trying what you have before making a decision.