>do these come up for sale fairly often on japanese markets
No, my impression is that it is very, very rare for a SZ-1 to appear for sale. I don't think that many of these were made to begin with. My guess would be 50 units, max.
>did you purchase yours new before the demise of Micro Seiki?
Yes, I bought mine in the 1980s. When I had an issue with it, Nishikawa-san was the person who took care of it (grin).
I've compared it to an 8000-II, which I am confident that the SZ-1 betters, but not to a TechDas AF1. I've only heard and played with the AF1 at various audio shows (the AF1 was first unveiled at the Tokyo International Audio Show a few years back, and Nishikawa-san enthusiastically walked me through what he had accomplished. This was before final production, but I still remember what a huge grin he had (smile). Most likely the AF1 is Nishikawa-san's chance to successfully conclude all of the uncompleted design work that he accumulated while at Micro (I know that feeling well).
At any rate, I took quite a few pictures of the AF1, and posted them on Audiogon AFAIR.
Today, I'd imagine that Nishikawa-san is back-ordered and ships every completed AF1 out the door as fast as possible.
I doubt that there is any demonstrator unit that I could borrow for in-home testing. Maybe in some months (not that I could afford one in any case - grin).
kind regards, jonathan