I'd like to know whether the people reporting zero fan noise are playing patched games. Seeing some reports of loudness in games that take full advantage of the system and hoping people might be able to offer more perspective... I don't think it's that surprising that some games that send a launch PS4 into jet engine mode don't do the same on the Pro when it's not running at full clockspeed.
I'm still at least a year (and probably longer) from a 4K TV, but I've committed to replacing my launch PS4 due to the noise issues. For me, the price difference on a Pro is $80CDN (trade-in bonus for the Pro), so it seems like a far better option... but I wonder if it's worth it if the noise level on patched games is going to be noticeably louder than a slim.