MB: I had both the 2015 and now have the 2016, after a long history of keyboard-related issues, with keys being sunk in, butterfly clips broken, the rubber domes underneath collapsed. All in all 6 swaps (who can remember), sometimes many weeks without a device. This was all either new/out of the shop keyboards, or something that happened within the month - not something I did to them with abuse.
My 2016 device was manufactured end of August. The keyboard feels somewhat different to the 2015 iterations I had before. But it's definitely NOT a significant redesign.
It feels *slightly* more accented, with a tiny bit more warmth and volume to the clicks. I think they did some iterative changes to the manufacturing (not the design) to make it more robust - maybe swap out the rubber dome plastics underneath - but as far as me liking it more, it's a tossup. This one STILL has non-uniform keys (some are ever so slightly slanted and feel differently). 2/10 would not buy again. 😀
Oh, the rest of the hardware is nice though.