I have been doing some research on bits, and training with different kinds of bit and stumbled across this thread. I see it is a little old, but hopefully will get some replies.
I have a 16yr old Morgan mare I started to teach to jump in May 2013. She has been in a mechanical hackamore (a really cheap version like you can buy at Tractor Supply) and switched her to a Herm Sprenger short shank hack when her owner said she has always been in a hack. She does fantastic in it, even on her moody days.
What I am running into now is that most shows around me don’t allow horses to show in hacks because they don’t offer the control that a bit does, so what if the horse goes wild? I am disappointed because for just a few months work (we are “off” now for the winter) she is a very smart jumper and I wanted to do a few small local shows. Because of this, I have thought of switching her to a D ring single link snaffle and have one of the correct size for her, but I feel like after 10+ years of hackamore riding, wouldn’t it be an uphill struggle to switch to a bit?