You MUST purchase a JB3 to record. The others dont have the capibility.
that's Not true , I own a JB3 and a Jukebox II (20gb version) I would assume the 6gb is the same aswell
The only diffrence I can find in the JB2 and the Jb3 is the Firwire compatiblity and a different Batt .
Both offer 16/48 recording option's.
I must warn ya though the Jb2 uses the batt's up pretty fast, so I would suggest building some sort of Batt sled to help ya power it,
and to answer your Original ?. A typical 2-3 disc mule show is a bit over a Gig, so you should be able to tape a couple show's safely without having to upload them,