I am by no means an experienced razor honer, but I am a very experienced woodworking tool honer and one thing I have experienced myself, and has always been actively talked about amongst the woodworking community, is the Norton Flattening stone not being truly flat and having some real quality control issues. I ended up getting rid of it and now use a DMT diamond plate to keep my sharpening stones flat and it definitely works better (for me at least).

This may have little impact on your use, but flat stones are a must (IMHO) to truly achieve sharp, and a flat reference is needed to keep your stones truly flat as well...