Heh. I'm raiding on about the same thing. The marks definitely vanished. And either I overlooked everything except yellow or ~60-80 yards was farther than my object draw distance. I DO have my setting below minimum though, as per this post:
http://www.reddit.com/r/wow/comments...ttings_macros/
Of course, one quick lap around the boss in melee range reveals them no matter where they are.
Edit: this is what
fighting a felhound with a mage looks like on my machine.
Edit2: By the way, Projected Textures hasn't been needed to see any raid mechanics since the start of Cataclysm. Only thing that ever had a problem with it was the bolts on Sha of Fear, and those have a particle effect over the impact point and you can watch the bolt itself as well.