I just bought an Xcaret Pro 99 18GB expansion bay drive for my Lombard. To install, you just slip it into the empty bay, and the drive comes right up on your desktop. It's very quiet, and not at all annoying even in a completely silent room. It powers down after inactivity like it should, and it powers down immediately if you drag the drive into the trash.
The Battery control panel usually says I have 3:25 left right after unplugging when I just have the CD-ROM installed. When the Xcaret drive is installed and running, I notice it says 3:05 typically. Not sure if I would get back up to 3:25 when the drive powers down.
Speed-wise, I have no numbers, but it has been fine for capturing DV and writing back to DV cam. No dropped frames at all even with 333MHz.
Best of all, it doesn't have the annoying ker-chuck ker-chuck ker-chuck! sound that the internal Lombard drives make every once in a while.