Good question and answer. I am poised to get the Bio 500.
I suspect its a case of adjusting the way you grip depending on the shot you play. Returning a heavy ball is bound to create the situation where a firmer grip is required, but otherwise I would try different ways of gripping to see what works. My only concern is going to a larger grip that works for some shots might not suit your all round game and overall grip comfort.
"Tennis is just chess with balls."
Sometimes: Dunlop Biomimetic 300 - Sometimes: Prince Exo3 Graphite 93