I've used Soul Treasures a few times. There are some really nice George Duke riffs in there. It's simple concept really - each riff is split into segments which you can time stretch, pitch shift, reverse etc. So you can take the original and twist it around until fits your track. You just have to experiment.
It's also really worth learning the ins and outs of Kontakt because you can click that wrench icon and get inside the instrument to apply your own effects chains etc. You're not just limited to the effects that are given to you on the instrument's interface. Kontakt has a ton of every kind of effect you can imagine from EQ and compression to delays, flangers, choruses, tape sims, amp sims and distortion. Like Reaktor, you can either use it to host factory and third party instruments without ever getting under the hood, or you can roll your sleeves up and create your own stuff.