If all you want to do is duplicate the functions of your existing remotes, you don't need the 8811 or JP1. However, if you want to create bullet-proof macros that will operate smoothly no matter what state your equipment is in, then having another remote to learn discrete codes from is the cheapest way to achieve this.
I usually recommend to those who call that if they're not sure that they want/need the package, just get the MX-500 and you can always add either an 8811 or Radio Shack remote later on. You can also get a JP1 cable (or make your own) for $18 delivered if you don't get all you need from advanced codes.
IRClone gives you the ultimate in flexibility with your MX-500, but it costs almost as much as the MX-500 itself.
Mike
www.SurfRemote.com