I've been going back and forth with support with new GCode for the MMU2s and it is looking much much better, and far more reliable. A few more tweaks an it should be pretty good with the current version of S3D.
One set of features that are missing in the current version is the lack of any smart infill or purge block for filament change I don't expect to see such enhancement in the current version of S3D however. Maybe in the next version.