I have to say that having owned the D1, D50, M10, D100, D10 together with a variety of Olympus, Zoom and Roland handhelds, then the best internal mics I have ever used were those on the D1 and D100 with the latter being the best recorder overall. For me it's not even something I think about now, the D100 is simply the recorder is use in most situations. It's expensive for a reason.
(I would also say avoid the D10, I thought it was very disappointing and will probably be selling)
As for the question above about the D1 and D100 mics being the same, I wouldn't be surprised because they look identical. Unfortunately I sold my D1 when I bought the D100 so can't examine closely.
One word of warning about the D100 mics though, they might be the best lowest noise mics available on a recorder but they cannot handle loud noise. The D100 is perfect for what I use it for, capturing quiet ambient sounds, and will be great for most music but not very loud rock shows.