If you run a small thread base down and then slide your bead over the thread it will help to keep the bead from sliding back and pushing your flys body back better than leaving the bead on a bare hook
I like the look of glass as long as my pattern doesn’t have a tail pretty hard to get that little bead over it sometimes so you don’t have a space and I like to epoxy them in place so if one breaks the rest don’t slide around unless you want them to of course