Wayyy too much anal retention over sizes, stances, and stats. My two cents: Get a board suited to your style instead of forcing your style into a limited selection of boards. IMO I highly doubt you'll be pushing your boards to their limits where you'll notice the difference between boards at such high speeds. So get whatever sounds more appealing to you.
Looks like the proto has more flex than the attack banana. I have the Attack Banana, and I never had buttering issues. My friends use the Skate Banana and also have no issues going fast so lesson of the story: it's up to you