Also, it is interesting to hear about bits as 'short cuts'. I believed that I should ride in a snaffle for 8 years of owning my pony, and when I introduced the hartwell pelham, he immediately seemed more comfortable because of the tongue room.
I searched for a snaffle with a port but didn't find anything suitable so I have taken the curb off of a kimblewick to use as a snaffle because it has a tongue groove. My pony is far happier, but unfortunately I cannot find a dressage legal snaffle with a port.
To get the point, I was surprised how much difference a bit could make as previously I was very snaffle, jointed or double jointed etc for my pony, yet he is happier in his pelham than anything else.
Of course, it is not a training aid. Bitting should be about making your horse comfortable, and I think that it is a shame that dressage doesn't allow the grakle noseband at lower levels (given that it allows the flash...) and does not allow the pelham at higher levels, given that some horses do not have the room for 2 bits in their mouths.