Being that the billet cases have to match up to the already designed transfer ports on the cylinder and work with the already determined cylinder spacing, there is not much they could have possibly done to make the billet cases flow better than OEM cases. Like jo5hi3 said, the benefit is eliminating the voids that previously had to be epoxied shut to get extreme porting and increased stroke.
A lot of companies spent a lot of time and money polishing the turd that we know as the 62t engine, I think we are now seeing the limit of it's capabilities, that is why EME uses Polaris engines and WDK and Xscream use the 66E base for their monster motors.