I just thought this was interesting. I put a hackamore on my mare to "test" her responses to my leg/seat..body in general. It gave me a lot of valuable feed back. I was really proud of her, she did outstanding.... except, one thing - she didn't move off of my leg pressure from a standstill (left or right). I only ever use bit pressure if I get a slow or no response otherwise. So, I am guessing that in the past I had consistantly had to go from leg to bit pressure to move out L or R from a standstill, but I never realized it. I think a hackamore (or halter if you feel that "sure") is such a great way to identify holes in training....I know I was pretty surprised to find that one!
And, I had to use next to zero pressure to get her to stop beautifully. She has always seemed unhappy about bits in her mouth. I even had her teeth checked twice, "just in case"..nada. I guess she just doesn't need one. :) I am not dropping them all together, yet...but I will "plan" her training in that direction.