Y'all haven't answered his question. Some companies give you a hat with the purchase of a new bow, others give nice window decals. Some give both.

Seriously though, like it's been stated above, you may gain some speed, may be quiter, may be smoother. On the other hand, you really may not gain much at all if you don't bow hunt that much. I've sold bows that I've regreted selling before. I've shot some that felt great in the store, but ended up not being any better than some older bows that I had a lot of confidence in.
If you just bow hunt occasionally and you're happy with the setup you have now, don't go shopping.