I did use one for a very short time. It didn't work well for me due to some limitations in the phantom power section. If I remember correctly, you can get about 28 mA from all four channels, but no more. There is a "zipper" noise when adjusting the volume on the channels, so you have to have your levels set prior to recording, or you'll run into issues.
I don't recall the size of the hard drive and it's a pain to replace it. The SCSI connector is the only ouput (other than the analog or digital outputs that happen real-time), and while it is faster than USB 1.x, it isn't faster than the USB 2.x and FireWire connectors used on newer recorders.
I have a hard time judging the sound. I was only able to use it for one show and I used it as a bit bucket since it wouldn't run my four EW mics at the same time. I ended up swapping the Deva II out for the Deva IV (it wasn't a straight up trade!).
The Deva II is the box that started the non-linear revolution as we know it today. Zaxcom won an Oscar for technology for this box. However, it is a bit long in the tooth, and while you can find these units in the under 5K market today, I'm not sure for what we do it's worth it. There are no updates to the unit, and the difference between the Deva II and the Deva IV, V, and 5.8 is like night and day. If you're serious about getting one, send me a PM and I can see if any of the Deva owners are close to you and would let you see it in person. There are also some rental shops that have these still (although most are now renting the Deva IV and V units), so that's an option to run one before you buy it.
It was years ahead of where anybody was, and there are some features on it that no device has on it still, but a newer generation Deva would probably be a better option for you if you're looking specifically at the Zaxcom line. However, it sounds like you're not.
Wayne