i took mine off because, as blue said, it was rubbing on the belt. and i had some headwork done at the same time so just never bothered to re-fit it. then i got a new one, painted it and found that the mounting holes for the rear screw were f**ked and it wouldn't stay on anyway!!
The "cool" racer look with potentially £4000 worth of f--ked engine Verses £18 " un cool " cover
thats the kind of thing my gran would say!!!
i know there is a risk but its got to be pretty slim. i don't leave mine off so people can see my cool blue pulley, its just a bonus of not having one!!