I ride, and train, all of my horses in a simple Eggbutt Snaffle. I've ridden TWH, MFT, and a QH all in my one, simple, copper mouthpiece snaffle.
Shank bits work on the principle of leverage. In my opinion, 99% of horses worked in a shanked mouthpiece are working in a bit that is far too much for the horse. I recently rode a green MFT in a shanked, ported bit. At the slightest touch of the reins (asking to whoa, very light handed) he reared. Why? The supposed 'patient owner/trainer' had spent the last two hours with his hands in his mouth, cranking on that shanked bit until the horse was gaping. I didn't have the nerve to do such a thing to the poor horse, so when I lightly
asked him to whoa, he whoa'd, with only two feet on the ground.
I prefer the Snaffle bit because it's lightweight and sits nicely in the mouth. It's perfect for working green, or trained-but-not-finished horses. Great for trail horses, if you need to put a little pressure on your mount you can without it going up-up-and backwards because holy **** what is that horrendous thing in my mouth
If I need to whoa
with a little more force, or do an emergency one-reined stop, I'm not jamming a buttload of pressure into my horses mouth due to shanks + a port. You simply cannot direct rein in a leverage bit without causing the horse extreme discomfort. A snaffle is meant
for direct reining.
In my opinion, the shanked bit should be left to the professionals in the advanced show ring. It looks pretty on a horse and conveys subtle rein cues better than a snaffle bit.
This site has a great article on bits: Bits and their Proper Use
The pivot point to where the reins are attached at the end of the long shank
-------------- (divided by) --------------
The pivot point to where the curb chain is attached at the end of the short shank
A curb with a 5" rein shank and a 1" curb shank will generate a force ratio of 5:1. Thus a 20 lb. Pull on the rein will result in 100 lbs. Of pressure being developed by the curb's "vise grip" onto the horse's jaw.
The 'gaited horse bit' is a bunch of BS. It's for people who are scared of their horses, henceforth get a nasty shank-n'-crank bit, and want a 'uberpurdyheadset'. If your horse doesn't arch and collect in a gait naturally, you have a lot more training to do. Gaited Horse Bits are like the Rollkur of the gaited world. Unnecessary and improperly used.