Now that the other horses are used to it as well, I do feel that there is more sensitivity possible with it when I ride with any contact. The sidepulls tend to flop around on their faces a little, and rides up the nose on contact, whereas the crossunder hugs and stays in place.
I like the sidepull better than the crossunder because I felt I had more sensitivity with it!
I used the crossunder on Cisco for about a year, so I didn't just give it a short trial (thought I should say that) but it was neither a Dr. Cook or Spirit or anything else you'll ever hear of because it was made by a local tack maker and made of lovely english bridle leather (it really was beautiful). When I began having such nice reactions from Tam with the sidepull type, I converted Cisco's to a crossunder as well.
Cisco seemed perfectly content with the crossunder...it wasn't any difficulty for him that caused me to alter the bridle. Rather, it was me and the feel it had for me. I found the lateral flexions very difficult in the crossunder with Cisco. It tended to cause him to tip his nose. When I converted it, it was much easier to convey a more level-headed flexion to him and he seemed to understand better. That said, Sue's flexions with Sunny are so much nicer than my own with Tam, but there could be other reasons for it, because it doesn't matter if I have a bridle, cordeo, or nothing at all on Tam, for a level, correct flexion, he can't do it as well as he used to and I wonder if it's because of the increased muscle in his neck?
So my point is, I think
, that everyone is different...FEEL is different. If one takes the steps needed to ensure the horse is willing and able to respond to the bridle as we expect they should (through ground work and patience) then really, it matters not what style you use. It's more about the finesse in your hands than the style of the bridle. Once a person is riding, if the time has been taken on the ground first (of course with the exception of those occasional issues that rehab horse WILL have!), the touch on the reins is always light and never forceful or restraining. Some say that one problem with the sidepull is that it can twist on the horse's face...well, if you pull on one rein hard enough, and the horse has it's nose stuck straight our while you're pulling, then yes...it will twist. But as with Sue and Sunny and Tam and I and many others here, if one doesn't really need a bridle at all (like Sue's flexions with Sunny) to convey an idea to the horse, then twisting doesn't occur, or where, exactly the tack touches the horse doesn't really matter. Tam's sidepull has never ridden up on his nose. I'm extremely mindful though, that I've yet to find what I consider the perfect construction of the noseband of the sidepull and I've liked more, the pliability of the nosebands I've seen on a few crossunders (usually the biothane ones). So I'm still seeking someone who will complete my vision of the perfect sidepull noseband which will be light but not too narrow, and buttery soft in feel so it hugs around the nose of the horse in a gentle embrace. It will not be built to withstand a fight with a horse, but built to be a refined communication point. Delicate and inviting.
My current reasoning for the use of the sidepull is that to me, it is more closely related to the cavesson in action (the side rings) and Tam understood it easily, and for discussing the actions of rein effects and flexions with traditional riders, I have so far found that this direct action of the sidepull translated almost perfectly from someone discussing the same actions while using a snaffle or other non-curb bit.
Now here is Sue saying that she likes the crossunder for almost the exact same reasons that I don't (or so far haven't) liked them!
So I guess the suggestion is to try both and see what works for you and Mucki!