Old habits do die hard sometimes. It's possible that they are unaware of the competitive comments they make.
Maybe you can very unemotionally say to them, when they make a comment is very simply, "I'm telling you *such and such* to share with you, not compete. Please don't compare this to your standards". I think something like that would stop them in their tracks and give them something to think about. Like I said, it must be done very unemotionally....just matter of factly and then move on to the next thing you want to talk about. It might help

sabby