I have been playing a bit with the ISO 100 files from dpreview and pushed they to the extreme and my preliminary conclusion is that the A7r III have a touch lower luma noise in the pushed shadows than the A1 but nothing I would get stressed out about. I find the A1 a touch cleaner per luma noise than the A7r IV when pushed actually, also at ISO 100. Still looking forward to final optimized support for the files.