Three right now, but am planning on buying shitloads of them, selling shitloads of them and eventually ending up owning either 1 or 2 or shitloads or whatever. I couldn't care less.
For me this is mostly placed in the Department of Noob: the needing to know and needing to have experienced. Right now, the sound is not so important as the feel - especially of the neck.
I imagine (er ... hope is a better term) that when I grow up, I'll be able to have the same relation to basses as I have with pipe organs, synths and other keys.
Doing a Hammond solo on a piano keyboard or a light synth keyboard can be done, but the specialist will always hear it AND I use a lot of energy emulating the Hammond keys' specifics on a keyboard with a different feel. I can't be bothered to do that anymore. Now is the time for fun.
I'm also used to practise the same stuff on different keyboards, for many different reasons, but one is it brings out specifics that can help me mastering the piece and expressing something personal about it. So these days, when I practise the low E on the E-string (half there!), I'll do it on all three basses.
Does that make any sense in a bass community?