I recently purchased a BLUE 4003 in August 2014 (6/14 build). Named "little brother" in honor of my younger brother Todd, who passed suddenly in February (older brother died 9 months later) and designed to replace my 4001 (to be retired to studio only). ANYWAY - There is a definite difference between the 1980 4001 I used on numerous records (including those I was interviewed about here in 2001 and 2004) and this bass. Obviously they are different models, but the 03 was intended to replace the 01 (according to Rickenbacker) with improved design methodologies.
However, though I personally don't feel it can REPLACE the 4001 in the studio with the 4003. It does make a great addition to the collection with it's tone and playabiliity. and DOES do the trick on the road (so my "baby" can stay at home in the studio(s). So - 4.5 out of 5 for MY personal needs.