Well, it seems I'm the only owner of a JP8080 to consider using winjplib to lib sounds. I finally contacted Roland and here's there response:
'duh?'
They didn't even know the software was on their website and denied that it was theirs until I showed them their copyright message.
After further investigation, the answer is 'no' (no thanks to Roland though). Winjplib DOES NOT work with the JP-8080. I tried some further things with it and found quiote clearly that winjplib doesn't deal with the extended sysex info from the JP-8080. Sigh.