Oh, the Voyager is amazing! I would take it over any Model D. I love what people do with a Model D, but it’s not the synth for me. I’d definitely take a Voyager though.
On the Matriarch, I’m guessing it has to do with the mixing, levels feeding the filter, etc. Like you say, I bet it’s identical with some careful patch setup. The GM has such a simple signal flow though, that I imagine it’s four times easier to get just the right mixing and gains. It’s basically instant for me to get a patch the way I want. The Little Phatty I had was like that, and I imaging the Sub37 models are more work in the same way the Matriarch might be.
I haven’t played a Matriarch, so can’t completely comment on that other than what I imagine the case to be there.