The Leica 50mm f/2 APO-Summicron-M ASPH is the finest lens in the entire line of Leica M lenses. At its best, can it deliver a superior large print when used on the Sony A7R versus its native Leica M 240?
The discussion has a distinct Leica M rangefinder lens viewpoint, taking into account performance issues applying to M rangefinder lenses in particular.
High quality image scaling was used to assess actual print quality at 36-inch and 45-inch print sizes, using the Canon PIXMA Pro 100 (sections of course, given the size).
How much does 36 megapixels matter for prints of that size? In Guide to Leica:
Includes scaled matched crops from each camera using the Leica 50/2 APO on both under ideal circumstances. This analysis represents the best possible differentiation based on the sensor resolution differences.
Image scaling using Photozoom Pro. Includes a general discussion and perspective.
Note that DAP has two comparisons in a similar vein but comparing formats: