I have a 4yo mare who’s just been started, about 6 rides so far. She’s going great, super relaxed about it all. I originally had her in a KK Ultra, which she seemed to like, but I didn’t love that it was pulling through a little whilst we were installing steering. I since switched her to eggbutt I happened to have lying around, single jointed but with a curved mouthpiece. I don’t really like this bit myself, she doesn’t seem bothered but of course hard to tell at such an early stage (it’s also a touch big).
I personally really like the KK, my older mare loved it, and the breaker certainly took to it very happily…is it worth looking at getting one of the Sprenger eggbutts (I’m particularly looking at the dynamic RS with flat rings), or hold off, see how she goes and once she’s got a little more under her belt, try switching back to the KK? It’s alot of $$ to spend on a bit if its short term, and I don’t have anyone to borrow off. I can do a trial from a couple of bit stores but of course that comes with a fee/incomplete refund if it doesn’t work out.