Embarrassing to say, but normal provides just the right challenge for me it seems.
Anyway, the texture pop-in thing is interesting. When do you start noticing it? I have had none so far (Chapter 13). The Spanish ruins level has been the least smooth so far, as it did have a fair bit of tearing and maybe even a bit of slowdown.
I'm starting to wonder whether texture pop-in is dependent on some external factors. I have a European launch PS3 and have only 720p enabled at the moment. Maybe the speed of the harddrive is a factor? Or newer revisions of the BluRay disc have better datarates? Or dirty lense or disc or something? Maybe it happens more in the second half of the game?
I notice pop in at various times throughout the entire game. After loads usually and after cut scenes or entering new areas. Sometimes it's just a crate or a stone monument or it can be an entire rock surface. It can last varying amounts of time as well. It's something that has been noted by various reviewers,so I wasn't very surprised.
I have a 20 GB with an upgraded HDD and the game is running at 720p according to my TV.