Eh, guess I didn't think of that. The old one I had had a breast collar, so I'd never had much of an issue.
At any rate, I talked her out of it just today. She wanted one to help her learn to ride bareback, and I convinced her to go without because the stirrups wouldn't be any help in learning to ride bareback (since bareback doesn't have stirrups. :P ) and Ruby (my mare, whom she's riding) has a broad enough back that she's not hard to bareback. She told me she wanted stirrups for trotting (Ruby's trot is extremely jaunty, and hard to ride even in a saddle), and I told her I'd rather she not trot bareback, since it's hard on her back and my friend is almost too heavy for her, I think.
But thanks for warning me of that, I'd honestly never thought of the possibility. I'll keep it in mind if she starts insisting on a pad again. XD