I agree with most of the advice you've been given here.
Think about it this way: If you take this to a grievance hearing, there are one of two outcomes. Either:
1. You end up still fired. In that case, you're no better off. And, there is a reasonable chance that your PD will not feel as warm and fuzzy about you. Although I tell any resident that I'm terminating that it's their right to have a fair hearing, and that I won't hold it against them if they do, the adversarial nature of a grievance hearing is certain to elicit negative emotions in everyone.
2. Your program is forced to keep you. They don't want to, but the decision is binding. Unless you can magically have a much improved performance, this situation is unlikely to end well.
Getting a LD eval is only valuable for one thing -- more time on tests. And even that is hard to get from the USMLE or for the board exams.
As to your last post, if that's the metric you're using to try to choose a new program, you are going to be disappointed.