So mmbongo I was doing some A/Bing last night between two similar basses, one active and one passive... the active being an Ibanez SR with PJ's and the passive an early 80's Ibanez Roadstar II P bass. My "base tone" is through a VT Bass, so that was on as a pre for both... clean through the VT, the active SR has more character to its tone, more note-to-note consistency, no buzz or feedback, just a really solid clean bass sound. The passive is alittle more unruly... not as consistent across all notes, not as much "character" to the clean tone, and kind of muddy compared to the SR at the same settings.
Enter Ibanez PD-7 Overdrive + Wren & Cuff Pickle Pie B fuzz... my chain sends direct signal to the PD7, then into the VT toneshaper pre-amp, then into the Pickle Pie with clean blend.... played the active first, and while it held up the consistency, the tone felt a bit lifeless, and I realized it was more smooth synthy than the distorted facemelting I expected. Plugged in the passive P, and the tone is amazing... playing dynamics are amplified as they should be through the dirt, harmonic fuzz overtones are audible but not overpowering, note-to-note playing remained punchy and distinguished, and space between playing let out deliciously tasty feedback that I can modulate with the tone knob.
I may be playing with a thrash metal group again soon, and I'll probably go for the active. Under a wall of heavy guitars, its clean tone and consistency will trump the P. But for nearly any other genre of music or single-guitar metal (where dynamics in the bass are heard, not just the fundamental or mid punch) I'd go for the passive P.