Why have you been recommended one for your Ponio? Personally I prefer french/peanut/lozenge link snaffles to mullen mouth bits as they sit better in the mouth
It depends totally on the mouth conformation your horse has and the level of schooling of the horse and ability of the rider as to what bit would work best for you both.Why does your saddler think a mullen mouth piece would suit your horse?
The bit you posted a link to is a fulmer snaffle. The idea of the long shanks being that they assist with steering and prevent the bit being pulled through the horses mouth.
I use a cambridge mouth kimblewick and since changing to that bit I have found that my horse is far more responsive to me.Initially the steering was not fantastic but I have worked hard schooling him to move better off of my legs and weight aids and now find it works great.I have good brakes in it,far better than in a jointed bit.However my horse is a lightweight cob with a fairly fleshy tongue and I find the port in the middle seems to suit his mouth conformation.
Read an article by Klaus Balkenhol who trains Laura Bechtolsheimer. He suggested trying a mullen mouth snaffle in horses who are fussy in the contact, as there is far less for them to 'mess' with and is as simple as they come. Felix was fussy in anything jointed, lozenges etc, so tried him in the mullen mouth and he immediately settled into a consistent, light and even contact. It is apparently good for horses with large tongues, which Felix had. I don't for one minute suggest that the mullen mouth is a quick fix - correct training is the answer, but you also have to look at what suits your particular horse to complement it's training. I have started my 4yo in a loose ring double jointed snaffle and he is very settled in it, so I think it depends on the horse.
ldlp, a lot of horses go more happily in a double-joint with a 'peanut', 'lozenge' or similar, which sits on their tongue. this kind of bit is totally symmetrical, which normal single-joint bits are not. hold one up by the joint and compare the two sides to see what i mean, the cheaper ones have one longer thinner side, one shorter and fatter, so the rings aren't level when you hold the middle. even the expensive ones where the rings hang evenly still are not totally symmetrical because the joint is always slightly offset.
the best combination between a single-joint and a mullen (which has no joint at all, so many horses take advantage of its mildness) is the Hippus, which has the joint totally incorporated into the barrel, so is mild, has no lump(s) at all to press into tongue, and is absolutely symmetrical. pm me if you would like to try one.
I have a myler bit that is jointed but turns into a mullen mouth under pressure, so you get the steering too. Find it gives me great brakes but he's been resisting contact (although that might now be down to other issues....)
My pony is only happy with a mullen mouth bit. Anything else and he gets cross and fights me...when I had the EDT out to him he had a look at the conformation of his mouth and said it made perfect sense that he would be happiest in a mullen mouth
I recently put my fussy-mouthed Arab into a PeeWee bit, which is a thin mullen mouth with shanks, and he's going very well in it - brakes and steering are fine and he's stopped fussing all the time. He has a fat tongue and low palate, like many Arabs, and a jointed bit was uncomfortable for him.
My ID loves his Myler mullen mouth. He's fussy in the mouth - doesn't really accept a single joint & hates a doube joint or peanut to the extent that he avoids all contact & is as stressy as hell - & this is the mouthpiece he finally accepted & wil work forward into. He'll work in a Myler comfort snaffle too, with or without a low port, but he never takes them forward the same. The downside is he can occassionally get strong in the mullen but given the overall benefits I just grin & bear it.