I have a question concearning the UF and SS 12k as well:

I own the naniwa set up to 10k, wich gives me the highest and most consist polish ever (under light magnification)
even better than C12k and GS16k stones

I have heard there are some Spyderco UF users that have negative experiences with the finish it gives.
I know itīs not a big deal, but I donīt want a finisher that puts scratches to the finish.
So Iīve heard some UF users get scratches FROM the UF.
The edge is still good anyway.

But the question is; did anybody encounter these problems,
and how does the SS 12k compare? Will the 12k put a better polish to the edge than the Naniwa SS 8k or 10k (my most beloved polishing stones)
Because I heard people complain about (although consistent) scratch patterns from the ss 12k, too

( yes, I hear a lot of stories...)