Jenzuwin, I've now had 3 Shukers built from scratch and each has been of superb sound, playability and build quality. IMO Jon is one of the best luthiers around and deserves to be recognised as such.
I'd say get a spec together and speak to Jon about what you want. He is highly knowledgeable and will be able to guide you with your choices.
Depending on the complexity, they can take a while to be completed but they are worth the wait.
Post your spec if you go for a custom bass.
(I recently had a custom set neck Jazz built by Jon. There's a build diary on this part of the forum if you wanted to check it out.)
Cheers, T