Nice post - You and I are just looking at things from different angles - like the blind guys touching different parts of an elephant, we see different things.
When I talked about an active circuit doing the most at treble frequencies, I was talking from the design perspective. I design audio gear for a living, and have a background in Physics, so when I look at making a bass sound differnet, I see the problem with a different perspective, and a different set of tools.
The pickups on most basses - the magnetic kind, have some resistance, which people talk about a lot, because it's what you can measure with an inexpensive meter. This is a very minor part of the sound of your bass. They also have inductance. The fact that, if other things are held constant (like the magnetic structure and wire guage), the resistance and inductance are related, is why people talk about the resistance - it's actually the inductance which makes things ound different, but if the 2 correlate.....
Aside from the resistance and inductance, there are some parasitic things going on in a pickup - interwinding capacitance and eddy current losses, which have some effect on its sound, but not typically as much as the inductance. The other important component in a passive bass, bersides the inductance, is...the capacitance of your cable. Between those two things, there is a resonance, usually the upper mids/lower treble freq range - somewhere between 1 and 5 KHz, typically. More on this in a bit, but first, a small diversion.
Besides the electrical side of things, thare are other factors that influence the sound of your bass. The location of the pickups is a big one - the harmonics they pick up are directly influenced by where they are. The filter varies string by string. The sensing window - its width and other peculiarities, determine some of the high frequency characteristics - there's a spatial comb filter there that you can't undo electrically with any practical circuit (and it also varies string by string). There are magnetic non-linearities inherent in the spacing of the strings and pole pieces - a blade gives a different result than single pole pieces. All of this contributes to the sound of your pickup, but....I'm going to now go back to talking abou the electrical side of things.
At low and mid frequencies (below the frequency of the resonance that the inductance of your pickup and the cable capacitance (in combination with the interwinding capacitance) set up), the electrical response of a passive bass (tone control maxed) is.....actually very boring. It's flat as a pancake - in the electrical domain. You can put tone controls on an active bass that vary it, but..those same tone controls can be put on a pedal, or your amp, and the result will be absolutely the same, assuming you use the same circuit.
In an active bass, the thing you have going for you that you can't do later in the signal chain is....you have an opportunity to change the loading on the pickup, and therefore alter the response in the high frequncy region. This (yes, it's a long and twisted road to get here) is why I say that the most important thing an active circuit can do for you is in the high frequencies. Yes, it's perhaps more convenient to have a bass and or middle control on a bass instead of somewhere else, bu the sonic result does not depend on its location. In the treble region (at and above the resonance of the pickup/cable load combination, you can't do the same thing on a pedal or an amp that you can do on the bass.
So, that's why we see one thing differently - I'm looking at the thing from what do I have to do to change the sound, and how would I design that. You're looking at it from a user persective. Both valid views, just..different, and complimentary.
As far as fingerboard material goes, I've owned a bass with an ebonite (the stuff they make bowling balls out of - it's hard rubber, essentially) fingerboard - a Kramer I had for 30 years. No other fretless I've ever picked up ever sounded like that thing. Unfortunately, no other fretless I've owned weighed or neck dived like that, either. I've owned fretless basses with wood fingerboards. A very different sound. I have a fretless currently with an ebonol (composite) fingerboard. Again, a different sound. My experience is that, yes, technique and tone circuits affect the sound of a fretless, but even with that, you can go places with one kind of fingerboard, that you just can't get to with another material. As far as "clank" is concerned, what I call clank is something I've never gotten from a fretless - the hardness of a set of stainless steel frets and what I get from my technique with bouncing strings off of them is something I just can't get from a fretless. You can slap the strings off a fingerboard, but I don't call that clank. We can choose to call it that, if you want - no problem either way.
All for now - gotta go be productive.
