I've had Duncan '59's, WLH's, Pearly Gates, and DiMarzio PAF 36th Annis before. I guess I know what to expect from PAFs. Yes, they have all been bright and snarly, especially when hitting the strings hard, but never messy and scratchy.
These, aren't PAFs, though. These are EMG's. Even though they're certainly PAF-inspired, based on the many clips I've heard before, these aren't meant to be miles apart from the 81/85/60 that I know and love. It always seems like there's a little bit more sizzle from the 57 in the clips I've heard, but none of that single coil scratchiness and ugliness that I'm getting. You even said it yourself, and I agree with your assessment: The new preamps are brighter and cleaner. There is more headroom and more of the harsh kind of high-end.
Either way, I guess I'll know for sure when my old 57/66 set gets here.