I am looking more at the successful implementation by Leica of intelligent adapters allowing S users to use Contax 645 and Hasselblad H lenses on their cameras. In my experience, this is seamless, no penalties whatsoever (my H lenses focus as fast as native Leica lenses, their leaf shutters work fine, correct exif data is stored in the files and there are even individual profiles in LR for each H lens used on a Leica S). If Fuji can replicate this for S lenses, then I will get a GFX as a second body. And I don't care that the S lenses are big and the GFX body small. I'd love to shoot portraits with the Summicron S 100 on a 50MP sensor, in a 4:3 format, with automatic face detection/eye focus. I've been using my XT-2 in this way, with the fuji 90/2 lens - it is so fast and accurate that I can use it in this way even in a studio, with strobe lights, without rechecking focus all the time (which I have to do with the S...). Just press the shutter and bingo...works even with the self-timer (shot my new FB profile photo this way, as a "selfie", with studio lights...absolutely perfect focus every time).