Any comparisons that I've seen to date have been done with older black logo models, but never yet with the last of them, displaying the red circle, which would be the comparison that I would be willing to send mine in for. I suppose it's possible that the numbers would come up the same, but with coating advancements not always announced, I suspect that those of us who have the red circle Leitz 7x35 may well be getting a bit more light through.
Someday someone should do a comparison with the oldest black logo, newest red logo and Retrovid all in one test. Such a legendary heritage there in this instantly lovable binocular.