My riding style is a hybrid of dressage and cross-country. I like to ride with a light contact and to ride the horse forward into the bit for transitions. Because of this, I prefer a snaffle for everything.
Yet my mare is a little too strong at times, and even though we school with the snaffle and she is accepting of it and transitions well in the arena and on the trail, there are times on the trail when we are competing with other horses or around scary things and the snaffle becomes fairly meaningless to her.
Because of this I have been riding in a Kimberwicke at times. Yet I am dissatisfied because the Kimberwicke has a curb action and can't be used with constant contact. So I have been contemplating: Either use a Pelham or double bridle with two reins, or perhaps she might prefer an S-hack with a snaffle and two reins.
What I envision is using the snaffle as I usually do, but when my mare's brains disappear I could have the S-hack or curb as a stronger "hey, listen to me" back up.