Well I really don't think the charge controller would have any benefit to our rigs unless you have some kind of wild setup with multiple batteries and lots of electrical add-ons like welders or inverters and such. The priority start is a good product and makes sense, but if you have an Avalanche it comes with an automatic battery sensor that will shut things down if you accidently leave them on so that there is enough juice to start it. Its a pretty intelligent system, assuming any mods you do don't affect the circuitry. All in all, I'd say both options you mentioned would be unncessary unless you have done some extensive electrical system mods.
Have a good one!!
Trev