You can run ua-5 > jb3 via optical and not use the hosa. Patching is the only reason you should need it (the hosa) now, either to patch your jb3 into someone else (It could happen!) or to allow another, unprepared jb3 patcher to use the coax output from your UA-5.
This is all assuming, of course, that you are using the UA-5 as a pre for your own mics or at least an a/d for an analog patch.
Also, speaking of chaining jb3's, if both jb3's have the newest firmware and you have a 4-pin > 4-pin Firewire cable you can simply xfer the show from one to the other after it's over.
(see the FAQ:
http://taperssection.com/index.php?topic=16338.0 section 120)
edit: clarity (didn't work, i bet)