I've seen a lot of interest in the K64, which has not even been designed yet, while the K16 is undergoing testing as we speak. The 16 can be tied in a serial chain to other K16s, creating in essence a K64, or even a K256.
My expectation is that a K64 will have a lower part count that 4 x K16s, making it just a little bit less expensive. That said, if K64 boards aren't ready by the time my chips are delivered, I'll be having 12 x K16s.
I expect also a lower part count than 4 of the k16s, just not sure by how much.