Hmm, asking a skoda dealer is great until.....

It's an RNS-510 not a Columbus. You and I know they're the same, but the dealer has trouble.

You've updated the gateway to avoid the battery-drain issue, so the gateway is now not what the dealer expecting.

Also, (sideways for a moment) my CECM is not the original one either (upgraded to 30byte).

....so dealers won't have all the answers.

And as a complete aside:

My phone is running Cyanogenmod, not stock Android. Bloat is gone, battery life better and I have more control. Sometimes the big guys aren't always the way to go. ;)

Skoda dealers have all the answers they need. If you go to them with an unknown due to having changed the car and related components from what it should be, then they're just going to say "Hmm, not taking a chance on that I'm afraid. If it fails an update you'll want us to replace it with a new one."  Same as the guy who distributed the modified firmware, I doubt he's going to contribute to your new unit if his handiwork buggers the thing. Chance you take though really.

But they are clueless (or at least uninterested) on this aspect in my experience even when you haven't modded anything. In my case I taught myself as they couldn't even understand a map upgrade when I approached them. Then a few months later they hired someone who did know a bit about maps, and he decided to try and charge me 280 for an upgrade. Ffs.