I had Black Dakota leather in my previous 5 series. I cleaned and treated the leather every 3-4 months and that was enough to have it looking like brand new at the trade-in after 2 years and 50 000 km.
Now 3 months (and soon 6000 km) in with my current Ivory Dakota, I've already had to clean the leather twice. And I had to resort to dye removal for the drivers seat.
It's clearly more work to keep it looking brand new. But it looks so damn good
Also, when ordering my car, I had a chance to drive a dealer demo with Ivory leather and about 5000 kms. Lets just say that drivers seat wasn't that white anymore, but I don't think it had ever been cleaned.