Default [Q] how to go back to stock keeping mine and my wife data?

Hello all!
I know that there is plenty of threads about going back to stock but what I want to know is if there is a way to restore apps and data of a multiuser environment after the rollback and eventually which is the safest way.
Furthermore.. that's a bit ot.. I've not backed up drm keys when I installed cm10.2.. what will happen when I reinstall stock? will I only loose bravia as I've previously read?

thanks!
Phone: Nexus 5 (hammerhead) since Nov 2013 Rom: Stock Rooted 4.4.2 + ElementalX Kernel
Tablet: Xperia Tablet Z (SGP311 / pollux_windy) since Aug 2013 Rom: CM11 Nightly
Smart box: iThink (YP-2000) since Mar 2013 Rom: Stock Rooted 4.2
Previous devices: Galaxy Nexus (maguro) HTC Desire HD, Acer A1 Liquid, HTC Topaz, HTC Diamond, many other older phones.