I had zero problems with my Izotope apps. I have Ozone 5 and 6, and Nectar elements. They were all on iLok when I switched to my new i7 6700K build (I have since moved them off of the iLok). I have a couple of their free VST's too that work OK.
I had to reauthorize Addictive Drums (may have had to reauthorize Guitar Rig 5, don't remember).
My X-Touch and MOTU 896Mk3 Hybrid required "Windows" to reinstall the devices but that was only because they were on different ports with the new build.
I have Sonar, Studio One 3 and Abelton Lite 9. They all worked OK after the hardware upgrade.