Yeah..... If it ain't broke....
Oh, and since you already have 6.0, a FDR no longer has nearly the same amount of pain as before. A lot of the apps now include data in their backups to Google. So when you FDR, you'll get back ALL of your device config (from Wifi passwords to your DND settings, etc) as well as all your installed apps, and in many cases, the internal data for those apps.
But that's just a fall back. If your stuff came over from 5.1.1 without any problems, don't worry about it. But some people run into all sorts of weird issues after the update, related to some data not coming forward all that well. But everyone is different.