Just the initial oil changes (engine, gearbox, diff, brakes) when purchasing a car. The GTR and GTS-t would be identical except that the GTR has 2 diffs where as the GTS-t only has 1, and also has the attessa fluid.
I can't really see the GTR being serviced more than the GTS-t, new engine oil + filter every 5000km (same as the GTS-t), brake fluid will be the same, gearbox oil the same, diff will be a little more regular however even that would only be once a year like a GTS-t. The brake pads will probably be a tiny bit more often due to the extra weight (~150kg).
I guess over time as I (or we) update the info we'll see what happens...