i've heard of others finding such alternative ways to stop their engines, and it sounds like a reasonable plan. after having to FSS's fail a week apart, i now carry a spare top cover for my IP which has the FSS lever cut off. if i ever have to use it, i'll see about these alternative shutdown methods.
on a related note, they do make a cover that uses a mechanical shutdown, it was found primarily in stationary engines and non-highway vehicles if i remember right, and it would be fairly easy to set up a cable linkage for one of these if someone desired to.
as for cleaning the FSS periodically, the challenge is that it has a permanent magnet included in it, so it'll be challenging to remove all metal debris from it, especially when that metal has snuck its way inside where it can do the real damage.
i haven't had any additional problems since i added strong magnets to the bottom of my fuel tanks and the outside of my filter. any metal that may be present will get trapped by the magnet in one of these places and not get into my pump.
and pulling the top cover of the pump is as easy at it looks, but the concern is that the FSS lever MUST be in the correct position when the cover is reinstalled or else you'll have a runaway engine on your hands. everyone i've read says it must be energized when you're installing it, but my experience suggests that it can be installed properly by placing the top of the pump in place about 1/4" forward of its proper position, then sliding it back to where it belongs and installing the screws.