I don't often look at DPR, but I glanced and saw this preliminary review, which others may have seen before:
Studio tests and samples: Leica SL: Digital Photography Review
It allows you to look at 100% test files with SL and RII (or Nikon, Canon, etc., models) for resolution and dynamic range. The resolution tests are necessarily a bit skewed because they had only the SL's zoom lens, whereas the RII is a prime. Nevertheless the Sony resolution looks noticeably higher in the magnified files. And the dynamic range tests are affected only to a small degree by the lens, and they show more noise at high ISO with SL. I'm not so interested in high ISOs, but the same data means more processing latitude with RII.
I wasn't about to get on a list for an SL. But it's nice to be reassured there'd be no reason for it, from the standpoint of these two aspects of IQ.