I had a quick look at the DR-100. I found its preamp to be mediocre, sounding about the same as the Tascam DR-1. When providing phantom power to mics, the battery life with AA cells was ridiculously short, barely lasting 20 minutes using drugstore AAs. With the internal Li-Ion battery pack, I saw about 3.5 hours when providing phantom power.
If you're looking for good mic pre's, phantom power and long battery life, I'd suggest stepping up to the Fostex FR-2LE (about $585 at Sound Professionals). Or get a good preamp like the Sound Devices MixPre.
Flintstone