Hi Jon & welcome to the club!
The main deciding factor for me would be whether or not you'd be switching guitars at gigs (w/out utilizing the effects loop, the furthur would be the less impeding when configuring your rig). A Series instrument would require a stereo or dual channel rig of some sort in order to make full use of its electronics.
From a price standpoint, used Series guitars seem to offer more bang for the buck, while a used Furthur would hold its value in light of the fact that they are a newer model~ there are currently less of them out there, and the annual factory price increases make a used one or a stage model that much more desirable.
Either way, you can't go wrong. In a perfect world, I'd order a Furthur or neck-thru Skylark with Series electronics & a different wood recipe.
