About Type-R:
A friend of mine's got a Sony 440 deck, which does MDLP and has Type-R. He recorded some materials in SP (which gives them the Type-R treatment) and sent the discs to me.
Having heard those, I believe in Type-R. It's like everything maintains their distinction, even if it's loud, "compressed" rock music (for you J-pop people, he sent me Shena Ringo). Type-R also maintains a sweet timbre and gives the imagery of a somewhat wider landscape.
If you're just after Type-R, and you live in the US, you can get the 440 or its replacement, I think it's the 470. Compared to buying a R909 or N1, you could save quite a bit of $$. The 440 was $150 at Best Buy for a while, for instance.
That's also why I bought the MT770. I honestly have NO faith in how Sony handles the analog section of their portables, and if I want Type-R, I'll get a cheap home deck when I'm back in the US. For now I use Panasonic's H.D.E.S. which is also good IMO.
About how the MT770 sounds:
OK, the day 1 impression.
When I bought this thing, I had the chance to listen to the MT770, and the MT77. What I thought was that the 77 sounded closer to that glittery presentation of the 831; the 770 sounded, well, slightly warbly. It's like looking at text through some kind of lens, so the text not only gets amplified, but also "arched" and changes in shape and proportion. The result is that the 770, while not bad, doesn't have the "pizzazz" of the 831, and seems to lack a bit in high treble.
Other than that, you can hear the 770 still sounds fine. The 770 sounds just fine with the KSC-35, but if you're using the MX500, the warbliness worsens.
What I found when I came home was that, the sound seems to sharpen up when you power the 770 on AC adaptor. The "warbliness" is gone and the sound is more like a quieter 831. This certainly could be some psychological thing... but it makes me wonder. AC adaptor supply gives the 770 2V, so if we make a battery box, get 2 rechargeables for 2.4V and hook it up...
All righty, that's all for now.