Manual shifting (especially downshift) requires some serious work if they ever want to plant Zfat on M3s. Primary reason why F90 M5s just feel like a tuned up 550i compared to F10 M5s which felt like r8ped apes in a good way
BMW is just being lazy not developing standalone DCTs for full M cars regardless of M xDrive. Smooth shifts and luxury are not what M cars are about..