Of those that you mentioned, DAT is the only one I could recommend, although DAT is dead. You might want to consider other options. For example, NAGRA makes a seriously good line of digital tape recorders (big $$$ though). Also, Sound Devices has just released a new line of portable hard disk recorders that promise to be excellent and overall, a reasonable price. You could always use one of the larger format Hard Disk recorders such as the HD24 or SDR/HDR 24 with a rackmount pre and put it in a portable case. These have an acceptable "out-of-the-box" sound but could always be upgraded later with better AD converters.

8)

A real good solution to the portable issue is a good old ADAT recorder. You can find them on the cheap all over the place and as long as you are only running one (not trying to sync multiple units) they are generally fairly reliable.