Why don't you just approach people before the ride starts and lay down your "rules". Then you won't have to yell at them. I'm having hard time buying your safety issue when you've riders grabbing jerseys. What if one of your regular riders is having an off day and has to pull out of the paceline, do you yell at him as well? I agree with all of your points but if your going to be dropped pull out rather than force everyone behind you to go around to fill the gap. If someone has to push themselves that hard to keep up their bike handling is going to suffer and they're more of a threat in the paceline than fading back. Your group sounds like that shouldn't have any problems filling a gap.