I "believe" the stock hotter plugs resist fouling better, which probably wouldn't be a problem unless you were stuck in traffic. I doubt you would have any problems leaving them in until it is time to swap them. Under full throttle, you are less likely to get ping with the colder plug. No ping is good, with ping, the computer pulls timing. I'd leave them in there if all seems well, unless someone pops in and says something I didn't consider or know.