BIrgit, I don't say anything to riders who use bits, unless they ask me about going bitless. If they are not ready to ask the question, they are not ready to change. I do not condemn any of my friends for using bits (and most of them do), and I do not go out of my way to promote bitless, other than to occasionally, where I can, put in a word for ALLOWING a bitless option. I even recently saw a clinic advertised, and it stated, "Snaffle bit must be used". Well, that's one clinic I wouldn't go to obviously. It's perhaps possible that they mean that riders aren't allowed to use a leverage bit, but still...the bias is out there.
I live in a bitted world. Most of us do. I have influenced more people by simply going about my business and they see what I'm doing. Sometimes they notice the uniqueness of Cisco's bridle and will ask about it. Some may ask, "you don't use a bit?". I only answer that I don't use bits. I don't even say why unless someone specifically asks me. Nothing more. So without ever saying anything, by only doing, and by "being the world you want to live in" you can affect change around you. You also attract a similar energy to yourself...so you may begin to see more bitless people, because like minds are attracted to each other whether they are conscious of it or not.
I think information like Alex has, from Dr. Cook, is important to know...just in case someone challenges you and feel up to a good argument. But me, I avoid them.
Oh...there was one time I did step in and give an unsolicted opinion. There was this one fellow who has terrible balance in the saddle and rides with his hands and his horse is constantly stressed and inverted (and he uses a tie down or draw reins). With all his gear, he can not get his horse's head down. So I did manage to explain to him that all the gear and the way he rides is causing it. When his daughter gets on this horse, with her better seat and quieter hands, the mare still goes inverted, but she stops stressing and calms down...even occasionally dropping her nose.
We got him once to remove it all and put a sidepull on her. She went beautifully! Next time we saw them, he had her back in the snaffle and all the gear. He is not ready to change. If I kept at him, he would then just avoid me. I would rather he at least be able to see what can be done without a bit if he sees me riding. If it's meant to trickle into his mind, it will happen.