I haven't handled the MK2, but I own a BK2. I also haven't handled the BK16, but I've handled both the BK17 and the Kabar MK1 (which are both pretty similar to the BK16).
The MK2 is going to be MUCH beefier than the BK16. It is 3/16in thick, with a saber grind, and a taller 6in long blade. The BK16 is basically a larger version of the BK11. It is a full flat ground 5/32 (.165in) thick 4 3/8in long blade. The overall length is also quite a bit smaller for the BK16.
The MK2 is going to feel like much more of a knife, probably greatly in part because of its full size Becker handle. It will also chop and baton much better, thanks to the extra size and weight.
The BK16 is going to feel more "bushcrafty", as it is a much smaller blade, and feels so in your hand. It should do small chores better, and your hand should be a bit closer to the work.
Kinda like apples and oranges if you ask me, but thats my take. Both are great blades, but very different.
Now maybe someone that owns both will help you out

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