Three other basses? Good, that means you also got the best one (that would be the Rickenbacker).
4 hours after downloading, I've just completed my first Jaco track. I cheated, as I already had the track recorded, using Trilian's fretless bass. Just had to go through and replace keyswitches and it's done. To get a similar tone, I used the plucked nki with neck pickup and a simple TH3 setup. Didn't care for the built-in amp sims.
The slide feature was a little disappointing, as that was my main reason for buying the instrument. Not a slam on Mr. Schlaepfer, though - nobody else has yet mastered bass slides in any other Kontakt instrument, AFAIK. Still, Jaco will be getting a lot of use here.