John
You may have right regarding OS compatibility, this have to be additionally explored.
As a matter of fact I still run my Z3100 on Windows XP. My Z is connected to computer that I use only for printing. On that machine there are only software for printing, nothing else. It works perfect all of the time therefore I never consider to upgrade it, I just upgrade software that I use.
Anyway this is still wining combination, photographers that want high quality prints on matte paper are moving to me from printing services with new Canon and Epson printers. Recently I have situation in which one of my acquaintance, well known graphic designer, and less known photographer ask me to print some photos. He performed test, although I didn't know it at that time. He gave same 3 pictures to printing service with new Canon machine, new Epson machine and to me. Later he admitted that he did not consider me seriously as I have old printer which he consider outdated, but somehow he decided to give me a chance as I help him to organize his first photography exhibition. He was astonished by quality of prints, and decided to print entire exhibition on my Z. When I saw the prints from other services I was surpriseed with lack of fine details, color cast and low contrast. It may be that they do not operate their printers in correct manner, but they are experienced professionals, so I wonder how it happened.
I have seen many times prints from other machines and I always like my Z print more than any other if they are on matte paper, and especially if they are black and white. This machine may be slow, may have some quirks, may lack proper support but in my opinion it is still printer that make top quality prints. As I already mentioned I like Epson prints more than that of my Z when they are made on photo paper.
I also need to mention fact that I use Z for making profiles for all other printers that I use. If one day Z stop printing I will keep it as machine for calibration if he continue to work that way.