I also use VC papers occasionally for contact printing - Forte Polywarmtone using an Ilford MG head. However this paper seems prone to Newton's rings interference pattern noticeable in even tone areas like the sky. I've not yet tried other VC papers yet to see if these patterns appear.
Using graded papers (Galerie) and the same set up these patterns do not manifest themselves.
I had that problem with Polywarmtone as well, until I switched to the bad etched "anti glare" glass in my contact frame.