While I appreciate people's justification of using assistive touch to prevent the home button from wearing out, I personally prefer just to use the home button as Apple intended it to be used - to me, it feels better using the home button rather than having to touch the assistive touch icon which is permanently on top of whatever app you're using.
I have AppleCare and conveniently have an Apple store close to me. If it breaks, I'll simply go down to the Apple store and pick up a fix/replacement.
Incidentally, ifixit have shown that the home button in the iPhone 5 is somewhat different to those found in iPhones of late. I think the iPhone 5 home button may prove to be more durable than the home button in the 4/4S but only time will tell.