If you're after vintage [u]tone[/u], a modern bass with a properly fitted GK pickup and a Roland V-Bass will do. I know because I use such a system myself. (although I don't have [u]extensive[/u] experience with real vintage instruments.) I quite often use the vintage P model for the occations when that sound is fitting, which is quite often, actually. It also does the Rickenbacker sound, which I like, and vintage Jazz and Hofner, which I don't use all that often, being partial to the more rock-oriented tones.
Perhaps sometime this summer, some afternoon when the weather is bad and I've nothing to do, I'll record some sound samples of these V-Bass models and post them on my web page..... so you can judge for yourself, eh?