I have a d16, not a d12. But to me the d12 seems to be either an upgrade from the d8 or a baby brother to the d16 (depends how you look at it). If I had to guess, I would speculate that the new d1600 will replace the d16 and the d12 will replace the d8. The d12 looks to be contained in the same case as the d16.
My advice would be to hang loose for a couple of months and see if the d16 is going to be closed out. I think the d1600 will ship this March.
I have been very happy with the sound and function of my d16. I suspect the d12 and d1600 would be equally capable, for the price.