So, a few changes have been made to my ride:
Firstly, I finally retrofitted the OEM Xenons I've had sitting around for ages. I hadn't tested any of the ballasts, bulbs or housings so I was a bit concerned that things might not work. But after wiring up and coding everything worked, even high beams. Just gotta code out a few bulb out warnings.
Also snagged a set of OEM cherry LED tails and swapped them in. These coded out just fine. Overall I'm really pleased with them. They transform the rear end of the car, and they scream "enthusiast!" to those in the know. I've only ever seen one other MK6 with LEDs, so I feel pretty special.
I've also ordered a set of wheels that will be coming in shortly!