We've all been reading about the various issues with people using USB-to-MIDI devices to update the firmware on the DT25/50.  I haven't had a chance to do it myself yet (I'm not a big MIDI guy so I don't even have any cables, and I haven't had a chance to grab some yet), but the interface I actually have is a Firewire-based Focusrite Saffire LE that has MIDI in/out.

In theory, Firewire vs. USB shouldn't make a difference; in the end it should all boil down to the MIDI endpoints, regardless of what hardware transport is used. Of course, in theory all of the MIDI-to-USB devices should have been fine...

Edit: Okay, after realizing I could've used smarter search terms, I found one person who used a PreSonus Firestudio with success.  Anybody else?