My two cents then..
What bitless to use depends just as much on the horse and riding as when you chose what bit to use. Good things with bitless
is that the horse doesn't have to have anythig in the mouth, some horses can loose focus on the rider because they can only think of the bit (which should be trained away tho I guess) and if the horse has a mouth problem it's good to use a bitless alternative at least untill the mouth gets fixed.
They're easier to see if they fit the horse and to find the right size and thickness.
You don't have to warm the bitless in cold days.
The horse can easly eat with it if you just loosen the noseband. (In case of a break or so)
When working with a curb bit, a bitless option for the snaffle effect is great since you only need one bit in the horses mouth.
It is often easier for a green horse to understand preassure on the nose (similiar to a halter which they're used to) than preassure in the mouth; so bitless can be a good idea to start a green horse in and later on when the horse has gotten used to the extra weight and weird stuff on his back, you can ride with both the bitless and the snaffle while introducing the bit. Less good things with bitless
is that lots of people just take one without really knowing how t works.
It's not always allowed in shows.
People use bitless instead of finding out what's wrong in the horses mouth.
People use bitless instead of teaching the horse to accept the bit (which can cause problems if others have to ride it or so on)
Some bitless is hard to work the horse correctly in.
People might think bitless is so nice, they get harsher in their hands than with a bit.
I'm all for bitless if it's used right, but I'm not against bits.
My favourite bitless is the muserola (without studs) or a riding cavesson since they're (as far as I know) the best bitless for replacing the snaffle when you work your horse in dressage.
If you're not interested in dresage, a sidepull is good. You can work with it if you need to but it's not as precise as the muserola, and it's a bit gentler if you're just going to trail ride and have a sensetive horse.
Riding cavessons is great for beginner riders or beginner horses, sice you can attatch a lead rope to the middle ring and thus have a fair deal of controle from the ground without disturbing the riders aids or mess with different headstalls unless it's necessary.
Hackamores (mechanical) isn't too clear to me, they're the best option for a bitless curb there is, but too many people use it as a first bitless since they think they need the shanks for controle..and that's like putting a curb on a green horse.
I don't know much about bosals but I imagine them to be difficult to bend and flex in, and they don't really have the curb effect either, but I think they're good if the horse knows neck reining. As I said tho, I've only tried it a few times and don't know it too well.
The ''bitless bridle'' and others like it, with running straps that squeese the horse just doesn't make sense to me. Some horses work in them.
The parelli hackamore is ''just'' a rope halter. Nothing wrong with that, I've ridden a lot in those and they work. But I imagine it being hard to ask for flexion or collection in them. I guess they could be good when riders need to train their seat and stop using their hands too much.
Did I miss anything now?
Anyway.. bits should be handeled carefully and so should bitless. Both are meant for communication rather than force.
it acts the same way as a bosal does, yet doesn't have the rawhide nose thing (which I guess is the bosal)...yet it has the two knots as pressure points instead.
I did not post that I used the Parelli Hackamore to start a debate, so don't bother trying to start one (not pointing it entirely at you)...I simple stated that i use it, and it works great....giving my opinion on that brand because I've used it.
Sorry but I just have to say this; it does not work like a bosal since the nosepart is yielding while the bosal is stiff. Not saying you shouldn't ride with it, but it's still a halter.
- English bitless (basically a sidepull, but for English horses)
Please show a picture of that? :)