It's worth talking to the owner, it's not an overly common bit so there is probably a reason he's in that instead of a more standard snaffle.
I've heard great things about the Myler bits - but the only way to really know if a bit works with a particular horse is through trial and error - and the Myler bits are a little too pricey for that.
I would have to disagree with this. If you know how a horse's mouth is shaped, how the bits work, and what your horse needs to be cued on as well as what they like, then it's not a problem.
For example, I know I don't want tongue pressure, I would like to work off his palate & bars, and therefore cancels a lot of bits out for me. I also know I don't want to put him in a curb because we do Hunter Pleasure and you ride in snaffles or kimberwicks. I also know he isn't hard in the mouth, just needs something with a little more pressure & different positioning than his other bit so he understands when he rides with me, it's work, when he rides with them, they're them.
Because beginners are constantly mixing cues up with him, a loose ring snaffle or eggbutt would probably best fit him so while I'm riding him I can separate cues clearly so he can understand what is asked of him better instead of being confused all the time.
Therefore I am looking at;
1. A ported snaffle.
2. Gives more pressure to his palate & bars than tongue.
3. A thinner snaffle to create that little more pressure.
4. Has a loose ring or even an eggbutt.
From there I have to find what bit that matches, figure out what metal I want it in, and see which one best fits my horse (size wise) as well as my budget.
I think you just have to really assess your situation and what your goals are first. Too many people think, "Well maybe we could do better?" then fiddle around with a million bits until they see a better result. That's just silly! I believe if you feel you can do better with a different bit, figure out why
then decide from there the direction you want to take.
Of course, once you narrow it down, you may need to try out 2-3 different kinds to get just that perfect one. But I believe we are discussing the horse people that purchase 10 different bits to decide which one then dabble a bit in that section of bits with 2-3 more until they find the best fit, correct?