Something to do with not having an FCC export license for the Endurapro's USB controller.
Okay, delurk time, first post etc.
I have two USB Unicomps, shipped to the UK from Unicomp themselves, and when I boot up, 'dmesg' tells me that the keyboards identify themselves as the Endura, like so:
[ 1.817142] usb 4-1: Product: Endura Keyboard
[ 1.817143] usb 4-1: Manufacturer: Unicomp
[ 1.817195] usb 4-1: configuration #1 chosen from 1 choice
...
[ 2.165340] input: Unicomp Endura Keyboard as /devices/pci0000:00/0000:00:12.1/usb4/4-1/4-1:1.0/input/input3
[ 2.165372] generic-usb 0003:17F6:0709.0001: input,hidraw0: USB HID v1.10 Keyboard [Unicomp Endura Keyboard ] on usb-0000:00:12.1-1/input0
[ 2.165388] usbcore: registered new interface driver usbhid
I reckon that the ID strings here are coming from the controller itself, not Linux itself (nowhere does the string 'Endura' appear in the kernel source, for instance). Presumably this means that either 1) either the Linux kernel or Unicomp's controller itself is lying to me, 2) Unicomp is engaged in the lucrative practice of smuggling military-grade trackpoint controllers in their non-trackpoint keyboards contrary to US export regulations, or 3) there's some other reason.
As to which is the best, I have a black Customiser 104 (or 105) and a beige Spacesaver. I love them both, but the spacesaver does feel a little more solid and rugged somehow, and I like the size a bit better.