Oh yes that.
I see two possibilities here.
1) It's for later desktop Mac hardware.
2) It's for later laptop Mac hardware (as well), because as my later understanding indicates most laptops store the VBIOS as part of the system firmware and not on a separate flash like a desktop GPU.
So far I have not found good/bad machine differences that I can confidently attribute to firmware (my research continues). If I discover anything, I would be happy to collaborate over analyzing the differences.
If you PM me we can discuss analysis of firmware. Door's always open