I can't compare it to Henry's Avantone suggestion but I used the ECM999 a fair bit back in the early days of MS Stereo field recording. It wasn't bad at all--maybe slightly bright in the mid ranges but still quite a pleasing sound and it took the knocks of field work quiet well.
I gather they're quite rare nowadays...what sort of price are they going for now?
I would consider the slightly more recent ECMMS-957, which works quite well. Great with a microrecorder like Zoom H2 or H4N. It's a bitch to get from a 3.5mm miniplug to two XLR's, though, so using it in the studio requires a bit of a Frankencable.
The version I used just took a standard AA battery which lasted for ages.
I'm not sure about phantom...the output was on a 5 pin XLR which then split to two standard XLR-3 connectors. I may have the manual around somewhere in a box in my garage. If I can find it I'll see if it mentions phantom.