Is there any way to copy user-defined patches from the XP-30 to the JV-1080 synth module? Perhaps using a computer with midi interface? They have the same engine but different sound cards.

Dunno about the XP30, but on the XP60:

Attach a MIDI cable from MIDI out on your XP30 to MIDI in on your 1080.

-> Utility
-> Transmitting sound settings
-> 4. Data Transfer
-> Transmitting data to an external MIDI device