I can tell you how this pair is going for me.
Owning MD`s since 2004 and constantly upgrading final to an UW+ this Machine is like home.
The crispness, the immiadiacy, the versatility and the ultrafast workflow on it i love to death.
It is proud digital and can be harsh, but man…it can be lovely crushing smoothness too on samples.
As 4 years ago i came along the AR mKI, and bought it why thinking about a replacement. No, they go so well along. The AR for its round analog bass, filter goodness, the MD for sizzeling Hihat madness and all kind of hyperbending percussions…nah, you know what i mean. Both have their place they shine, both stay. i clock them from my multiclock with the same shuffle, which brings them together nicely.
as above, they are a great pair but objective on channel count, the MD is more versatile - 16 same channels vs, 8 with pre configured synthesis set.