Yeah, we can't really talk about the Pro at the moment, at least not in any detail. I'll get in trouble if I promise something that we can't get working in the end. I can say that, since the resolution of the headset doesn't change, any Pro upgrades we may make can only do so much to improve the visuals at the end of the day.
I had to look up the term 'mura' (you learn something new every day) but I can confirm there is a requirement for us to avoid black smear. I don't think that's what you're seeing, however - the 'film grain'-like effect is, I believe, an artifact of the screen door effect reduction process Sony are using. Again, I can't really go into detail on how I know that, but I'm confident that's the case.