+1. Just like the coatings on Leica lenses, although there've been some very heated arguments in the past from anti-UV-protective-filter advocates implying that they are scratch-proof 😕
Interesting as to the origins of that viewfinder coating. There were a lot of complaints during the run of the M4-P to M6TTL about viewfinder flare-out. At the time of the M6TTL the internet forums were just getting into swing, so a whole group of Leica users suddenly realized that many people had the same complaint, and Leica I guess felt they could no longer slough it off. So when the M7 came out it was touted to have a "solution", which turned out to be that coating. It didn't do squat for the flare-out, and a year later when the MP came out Leica had revised a couple parts inside the rangefinder. Shortly they put those into effect in the M7 too, and offered anyone who had bought an M7 in the first year to upgrade...for $285! despite all those cameras had 3 yr passports and were in-warranty (US). Somehow the AR coating stayed, and is present on the M8 (and probably M9) as well, even though it really doesn't do much.
My 40 year old M4's have no such coating, but they do have the pre-costcutting rangefinder parts that were added back to the MP. Those old cameras (well beaten BTW) have no scratches on their un-coated finder windows.
