Well, do you prefer a testbed box, or an emulator? Emulators have nice debugging information unavailable on a testbed box, because its lower level than any debugger, but a testbed box is sometimes better, because emulators are after all only emulators of a real box.
For myself, I usually test in MS VirtualPC, because JoeOS loads a lot faster on 2.4GHz than on 166MHz, but I often test new big stuff on poptart, my testbed box.