I am sorry, I am not experienced with them. Actually, I just used GB recently, and my personal IMMATURE understanding is:
GB model is mainly to attain quantitative agreement with PB results. And even for such a simple goal, it is still parameterized to attain it. The GB formula, to me, is doubtful.
Therefore, I gave up GB. And since PB is not expensive to my problems, I am using PB.
I think we need get comments from those more experienced persons.