I got my iFaraday today, only complaint I got is that the firm tip one leaves a black residue wich I'm sure is just a defect and you still have to apply quite a bit of pressure for them to track properly. Still better than the rubber tip ones, just gotta get use to putting more pressure than I'm use to.
Sorry I missed seeing your earlier question.
On the screen smudges---that happened to me too. I think Rustle (the iFaraday guy) got hold of a bad batch of tip material. He replaced them for me for free. You might want to email him about it.
+1. Get in touch with Rustle. I have a firm tip stylus and it does not exhibit this behavior AT ALL. In fact, the iFaraday "glides" across the screen with far less pressure than any other stylus I've used.