Thank you all for the considered responses. I realize that my issue are very much my own, and I don't want to imply that the gear is not good or is somehow lesser than that from other manufacturers. It is just not working as well for me.
So I guess I will respond in order:
Marc -- that is a very good point, and one I have been considering very carefully. At this point though, the M9, if it is real, is of more interest to me than medium format digital. I really like film for medium format, and I like the idea of a higher MP digital M camera, with M lenses. Bringing an Mamiya 7II with black and white and an M9 is a light, extremely high quality digital/film kit that is light and takes up very little space.
As for price, my Hy6 was new, and my 54LV was used, so total price was just under 15,000. That is barely more than the CFV-39. Today, I would be lucky to get 5,000 for the back and 3,000 for the camera.
Thomas -- Well part of the draw of film for me is that I am a lab. I have started a custom printing and processing lab here, so I am set up to process and print film already, with a good darkroom and enlarger, a very good scanner, a jobo for processing and so on. It is easy for me to get better results that way than it has been with the medium format digital files.
I am not sure why I have not been able to crack the digital files from the Sinar back -- they just look so digital to me...or perhaps I should say un-filmlike. The colors look wrong, the characteristic curve looks wrong (too flat, no shoulder for the highlights and shadows), the files are always underexposed out of the back, but not consistently so -- so EV compensation does not work well..files tend to be between -.3 and -2.0 EV underexposed, even with center weighted metering. The highlight behavior is weird, with color casts in blown out highlights. I could go on, but I don't think it really matters -- they just don't look right to me, and I don't want to spend 20 minutes with every photo to get them right. I have not had to do that with any other camera, film or digital, so I don't really want to have to do it now. The files I am getting are too inconsistent for any batch corrections or actions that I have the skill to create.
I would like to say that, while I am no digital guru, I know that I shoot well enough to get slide film spot on every time, so I don't think it is any failing in my shooting technique, but in the way the workflow is set up on the digital end. I am sure that many people could easily crack this, but I have not been able to. More importantly, I don't WANT to have to...as far as I am concerned, they should look good out of the box.
As for why I got the Hy6 in the first place --- I had a Rollei 6008 AF that I had been shooting for film. I had several lenses already, and I liked the lenses very much. I did not like the size, weight, metering and battery issues of the 6008AF, though I loved the grip, viewfinder, ergonomics and film back system. The Hy6 solved the battery, size and weight issues, while keeping all the advantages. It is a superb camera, but it does not shoot 6x6.
Steve -- thank you for the comparison of the general raw output of the four manufacturers. I agree that if Hasselblad has a similar sort of philosophy, I would probably be better suited with Leaf or Phase. Leaf would be a good option for the Hy6, but they are pretty much gone, right? Will the Leaf files be fully supported in Capture One (as well as they were in Leaf Capture)?
In all, I think the best solution for me is to just wait a bit to see what happens to the market for Hy6/Rollei 6000 items. The losses can't get much worse (well, other than for the back), so just waiting a bit until things are clearer in the market, and hopefully a bit of a economic turnaround.
Finally, I want to apologize to those of you who really love the Hy6 and Sinar backs and are doing great work with them. It is not my intention to trash it, and my failure with it is surely due to my own lack of skill and patience with the digital medium. I did not intend to make this thread all about me, but I just wanted to respond directly to those of you who had questions about my issues.