After pulling just about an all-nighter researching Pyramix and DSD vs. PCM, here's my initial impression.
DSD - I don't think we'll see a better way to capture an audio signal in the digital world for quite some time. Having said that, It's a PCM world for the working engineer.
I see the benefit being this. Capture your audio in DSD, downsample to a PCM-friendly file in any number of formats, and it's off to the races with your favorite editor / plugs. God forbid anything happen to your files along the way in your DAW of choice, you still have the DSD master, which is apparently audibly superior according to just about every opinion out there.
Pyramix - I like that you can import and export just about any type of file, and can enjoy the benefit of the 32 bit floating point architecture. Limited processing, but what's there is allegedly quite impressive. I would be interested to find out how a PMX crossfade would hold up if exported into another DAW though, since opinions on crossfades in some DAW's seem to be a bit of a touchy subject.
Overall, I think that Pyramix is on the right track, but without a greater proliferation of SACD, I can't see a DSD-based DAW making the kind of impact that PTHD has. In addition, after digging around a bit, I found an interesting piece of imformation in an article from Pro Audio Review in which Phillips and Merging agree that hi res 32/352.8 kHz PCM is transparent for DSD conversion to PCM...Hmmmmmm
I do believe that Pyramix would be a viable option for me...another platform to add to my short list (currently considering Nuendo or Logic in conjunction with Live 4).
I hopethat my observation/opinion is useful to you in some way.