first issue: I believe you need the digimod so you can go optical (digital) out to your MD, same goes for the JB3. someone correct me if I'm wrong, I'm just making an assumption from what I've been reading
second: you can't +T anyone yet until you get 50 posts
well, almost....the mod doesn't just enable the optical, it allows it to be used without a computer hooked up by usb, as caymanreview said, standalone.
both digi outs are available simultaneously i believe, regardless of how it is being run (usb connected or standalone).
these have gotten some great reviews, especially with the oade mods. i am not yet certain of their status on being bit perfect however.
and if you want the oade mod you must buy the ua5 from oade, they will not mod other units.