everyones different,
but on my gnarley, snakey self bows, i dont like to put tip overlays on, i like to keep the focus on the stave, but on anything laminated or with a backing, or even a very straight selfbow- then i put overlays on, and the glass bows get them too obviously.
if using FF, just pad the loops i believe- i use b50 right now, but when i buy again i am going to try some FF.
i have tried all sorts of tip overlays, but i have come to the conclusion lately that the best overlay material for me, is horn( not antler- but horn) works up easily and beautifully, and has a real depth too it- but thats just me- but i can appreciate all the other overlays too!!