I'm considering having another saddler come out and look at her because a horse that sweet on the ground cannot just turn into such a horror to ride... Or are some horses just like that?
But back to serious questions again. Like I said before, how can such a sweet horse be such a pain to ride?
Should I have someone else fit her for a saddle again? Can that really make a horse buck like a bronco?
If she is the same way bareback, it could be something more than the saddle fit...like maybe something with her muscles in her back, or something else out of whack; so someone who knows chiro or massage could help in that sort of case.
However, if those sorts of things have been ruled out (and it sounds like they had, in your other posts), then we need to chalk it up to her possibly just not having a whole lot of respect for the rider. If you have access to someone who knows how to work with horses like her, it could help to have them come out and see how she does with them. If she does fine, then we can assume that it may be something between you and her that needs to be tweeked.
I have seen several instances where owners believe the horse respects them from the ground, when he is really giving them a half hearted effort, so of course, when you go to ride, that 'half hearted effort' isn't going to amount to much.
I worked with a paint gelding one spring, who the owner and another trainer had been working with; by the time I got to him, they couldn't even saddle him, let alone get on. I had asked how his ground work was, and the owner said he was great in the round pen and lungeline. When I got there to evaluate him myself, I discovered a horse who was very much only giving as much as it took to get his handler to stop whatever they were doing, or asking him to do. I immediately decided to just do some roundpenning, and get him moving out off lead, before asking him to move out on lead. He had very sticky feet, and kept wanting to turn out and away from me on the turns, but quite quickly he figured out that this was not going to fly, and he started doing the round pen exercises correctly. I then got him on the line, and got him yielding his hips, and shoulders, backing out of my space, etc...when he was doing these correctly, then I started the desensitization exercises, starting with a bareback pad...pretending that he didn't know anything about being saddled at all. On and off I took the pad...approaching and retreating, until he was falling asleep, then I put it on and fastened it, and resumed ground exercises. When all was said and done, he wound up getting saddled with no line attached...I did some free lunging, invited him into the circle, and did all the desensitization exercises with the saddle pad, and saddle, before putting it on all the way, all with him off lead, and falling asleep.
SO...don't settle for anything less than stellar effort from her; really...you will get more results if you get exercises to help develop control and feel for each other, and not settle for "okay" effort from her, than you will by just skimping by, and hoping for the best. If it takes longer to get there, then so be it, patience does pay off, and I would rather have a horse who understands without a shadow of a doubt what I expect from him, than one that questions it, and winds up hurting us both. You want a "yes, ma'am" response from your horse when you ask him to do something, not a "fine, whatever, okay..." type response...