Np, I don't think that patch should require you to do much and the stock ROM shoudn't really be any different (if we're talking about the Android Factory Images[1]) than what you have right now so the patch should work without flashing any ROM. If you're going to flash and wipe everything by flashing it (and you're already stock Android), then might as well try the patch first before flashing the stock ROM.

Oh if you're rooted, then just use titanium backup if you want to be safe :). Good luck.

[1] https://developers.google.com/android/nexus/images