Removing mesh smoothing with DDX/DDY, but getting artifacts

Hey guys!
I’m using the method outlined in this old post (…ng=&viewfull=1) to achieve this effect, but I’ve run into a snag. The method seems to be producing some extremely unsightly moire ribboning when viewed up close, which are also causing lensflares and such to flutter uglily when bouncing off it. Can anyone think of a solution for this?

Use camera relative world position.

I love this forum. Ten minutes, BOOM - fix is posted. Thank you, sir.