And can someone tell me what the difference between the french link with the little dog-bone link and an oval mouth like those pictured above is?
I tried my horse in a Sprenger KK, which, of course, he loved, but he really likes to switch it up in bits, so I don't want to buy one until I know he'll settle with it- which he won't- so I'm thinking one of the above may be a good knock off.
Anyway, am I gathering that the peanut is just a more "anatomically correct" version of a double jointed snaffle?
I believe they are legal bits.
The JP snaffles have lots of different mouthpieces but the chief selling point is the curved sides. You can see that better in the first bit's photo. I have a couple of these bits and I really like them for green horses. They lay on the tongue nicely and don't pinch the corners and on the green horses, where you are making lots of corrections until they learn what the half halts mean, that helps. I think the JP's are milder than the straight counterparts, no matter which mouthpiece you use.
I have one 5 1/2 in. full cheek JP that fits draft crosses beautifully and they are hard to find comfy bits for - lots of them have low palates and wide tongues - these bits fit them very well.
I personally am a real fan of the three-piece snaffle either with the oval bean style center or plate center. Most of my horses like this kind of mouthpiece, it seems, and I have used the three-piece on one horse in my barn almost eight years straight.
I also think the bean style center is milder than the plate style.
Does that help?
I like the JPs. They function very like the KK and some horses fit/prefer the curved mouthpiece better. Both are legal and their is no longer any rule about the type of metal, so those are fine. I tend to like the lozenge better than the french link, but it is just based on anecdotal experience with my horses