You cannot beat getting hands-on with the instrument.
Some good points in this thread, but all to be taken with a pinch of salt unless they're referring to the bass you're looking at. I've owned a few Warwicks made between '94-'04 (SSI, SSII, Thumb BO, Streamer BO, Streamer Std), 1 was a dog, 1 was a gem that I shouldn't have sold (the one that got away!) and I was reasonably happy with the others. All played differently though... you need to get hands-on with it to really have any idea what it's like.