Back in my 'CB' days, all the sump plugs (Honda at least) were magnetised. Isn't that still the case?
I always fit magnets to sump plugs, cars or bikes, I have not had had anything worrying on the cbr, but it is a bit like fishing, When you change your oil you always wonder if you have caught something, only difference is if you have got a big lump it is worrying,
They are good to stop some of the particles going around the engine, but a worry is that if the magnet was to work its way loose it would cause more damage than it prevents. Ive used them on other bikes with no issues.
I must admit that thought has crossed my mind, I machine mine out on the lathe and make them a push fit in