Newer and older Rickenbackers are two different animals. For a more "idiot proof" instrument, if there is such a thing, I'd stick with a newer 4003. If you are not very handy and don't like to screw with your basses the newer 4003 is a safer purchase. If you can't put your hands on an older 4001 and actually inspect it or play it, the newer 4003 is a safer purchase. If you don't know a whole lot about older Rickenbackers and how they operate and what their idiosyncrasies are, a newer 4003 is a safer purchase.
Here's my disclaimer. I like certain 4001 basses better. I like the hairpin truss rod system, the long pole toaster sound, the checker board binding, and the real magnetic horseshoe pick ups. I do own a few 4003's that are simply awesome. My 1986 Shadow is one but even that one can't touch my 1965 4001 in sound or feel.
The foto is proof that I have a bit invested in the brand and my words are backed up by action and not just air. Missing fromt he foto is my 2011 Jetglo drop D 4003.
Sepp