I run a kill on my elcan, custom protectors on my eotechs and i havent yet but (should) get one for my aimpoint. I havent gotten one for any rifle optics yet.
Ive seen many optics saved from killflashes, Scooby's aimpoint killflash had a round imbedded in it last year lol. Ive been hit in the scope quite a few times, i dont like taking chances