Getting a headset with this...

My barn manager's trainer is trying to get one of the older two year olds in a head set while ground driving so she can transfer it over to riding come this fall when they will be backing her. She is thinking of using something like this:
http://www.doversaddlery.com/dover%9...1-3018/cn/109/

I think that if something goes wrong the filly could severely injure herself, since she is a young horse. The trainer is obviously experienced and has trained many in her life but but I heard her talking about using Chambon on the filly so I looked it up. My barn manger is very la-la whatever about her trainer and sometimes I think the trainer is too harsh on the foals (and sometimes reckless just to get the task at hand done) but Nancy is never around watching to see what the gal does. I have never seen a Chambon used and so I have little to know idea of how it would work essentially.

Do you think it would be dangerous?

Yes, but that's just my initial reaction after seeing it - I have never used one and so I wouldn't be at all comfortable doing so.. but my initial reaction to the looks of it was "yikes!"
I'd rather use very loose (and very flexy) side reins.

From my understanding when the head is raised it applies both poll and bit pressure, if the pressure scares the filly since she is young and still learning to give properly, she may throw her head up higher and push against it, even worse she may rear or tear up her mouth or bruise her poll or a number of other things.

I don't see why she doesn't use side reins, why use something so dangerous? I think that would be better suited for a more finished horse, that is about four years old and getting ready for a show or something...

You hit the nail on the head right there.

Do you think I ought to mention something to my barn manager? I am on slight bad terms with her ATM because I finally blew up at her about her not saying anything to Jack about the whips and she has been a little distant, she still calls to see if I'm coming out and to see if I wan to ride out with her though. I don't want to seem nosey or something, I mean its her horse but I don't think she knows. I'm concerned for the filly.

Well, ask her. Act like you are really curious and wanting to learn her way of training. Ask her to explain it to you. That is one thing my dad always did when we were younger. He would explain the why as well as the how to.

It is okay to be nosey if you are wanting to learn. If you go about it the right way, you may get a satisfactory explanation of why she is doing things how she is.

There is a barn near me which uses them and I don't agree with it. In the right hands they are relatively safe to use. I would use standard training in saddle and on the ground and stay away from these.

If she's ground driving why doesn't she just put the lines through the bit like draw lines? It will help/encourage the horse bend its neck but theres release in case the horse reacts.

The chambone is a wonderful tool, and as others have said, if used appropriately and correctly. It's a non-restricting mechanism that encourages the horse to lower its head and get that "long and low" look which helps strengthen the topline. For a young horse, start out really loose, and go up from there. I've never had a horse react badly to it, as it is pretty mild. Unless you crank it up on the first attempt.
What's great about it is is gets the horse very soft. Head goes up, pressure on poll and bit. Head goes down, all pressure releases. Unlike side reins, which teach horses to lean on them, they are unable to lean on the chambone. The young horse can start to learn how to travel with it's back up by having his head being encouraged down.
I think you should analyze the situation, but I really like the chambone. :)

How old is the filly? I forgot to ask.
I don't think the chambone should be used if the horse hasnt already learned to lunge and accept the bit and knows most aids. I wouldnt ever use is as something to start out with. :)