Well, my actual modding experience is rather low, except of toying around with other peoples work and doing a few quick and dirty mods for my own use. So I'm not completely ignorant to Oblivion modding but won't build the next huge overhaul soon either.

Point is, I really don't have any experience on how safe it is to have unneccessary scripts running in the background all the time in Oblivion. I know from other (older) games that permanently running scripts should be used with care as they're using up memory. Therefore I was trying to find a solution that would only call a script once in a while, do it's job and then go back to sleep.
However, if some experienced modder can tell me that it's safe to have a script running on my companion all the time, check if they qualify for an item/ spell upgrade and do the item/ spell swap if required, then I'll do it that way.