I had the chance to visit Wilcutt Guitars in Lexington, KY, today and play a 4001C64-FG (10/2009), a 4001C64S-MG (09/09) and a 4001C64S-JG (also 09/09). All were beautiful instruments, but I had to give the "playability" nod to the S models. The overall finish on the FG C64 was gorgeous and the glossy finish on the fretboard really made it pop. However, the neck was noticeably thicker than either of the others and the finish on the back of the neck felt, for lack of a better word - tacky. I just could not feel myself really cooking on that bass. I've had the same issue with my '08 4003 MID, but it was much more evident on this bass.
By comparison, the feel of the satin finishes on the S models was superb, although the fretboards were visually less arresting than the FG. Both neck profiles were smaller, although slightly different in profile (the JG being more D shaped, the MG more C).
While 2 of these 3 basses were poorly setup, the tones produced by the toaster and horseshoe PU's was awesome - far more varied than any of the hi gains I've played on 4001/4003's. In the end, none of the three reached out and grabbed me by the throat quite enough to compel me to trade in the '08 4003. Still, it was a great way to spend an hour and change.
Matt B.