I'm also wondering this. Picked my a 59 plate yesterday with RNS510. Would just update to the most recent software available on the web but I've read in a couple of places that the current firmware might be too new for my unit???
Also, that you need to update in increments. So from 2009 to 2015 your need to do many. Seems crazy!
Reluctant to give it to VW - they're bound to overcharge.