I'm running PS2 on Windows 8.1 preview. It runs smooth like butter and does away with many of the UI issues desktop users have with Windows 8 (I'm not one of them btw). And as said, the issues some developers have with the closed shop is not relevant for this game or any desktop gaming. They're just afraid of being totally cut out in a possible future OS version, which I won't see happen honestly. MS is not stupid enough to screw over its own desktop developer eco system.
So if you're not having any issues with the new UI, there's not really a reason not to play PS2 on Windows 8. Having said that, performance wise
there's not much reason to install it either.
The only reason from a gaming perspective is DirectX 11.1 (
some features in Win7) and 11.2 (
Win8.1 and Xbox One only), but for this game that doesn't matter at all.