I would like to hear your input on this...
I have experiemented with various values of tone caps and found they cause different roll off characteristics in the LPF aspect of the EQ. As the cap size gets bigger, the roll off goes deeper in the mids. A .015uF honks, a .1uF is pretty much all bass. I don't really hear a cap to cap value difference until the tone pot is turned down below 5 or so. Maybe it's my dull, forgiving ears, but I don't hear cap differences with the pot turned up.
However, changing the pot values has had a pronounced effect on the sparkle and air, especially when on 10. When I hooked up some SFs to a 500KA tone pot, there was a little more air when on 10. A 500KA volume pot sounds like it shifted the resonant peak up and added some brightness..? I have found the taper and treble loss when rolling down 500K volumes less appealing than 250K volumes, though. But if one wanted more aggressive top end, maybe the 500K is the way?
There is also that factory .01uF treble bleed cap in my SF Peaveys. That also helps keep it shiny sounding when turning down, though I find that value a little too clanky. I go much smaller to keep it more focused and sparkly up top. However, I rarely run my bass volume on anything but 0 or 10, so it's not really a thing.
In the end, I prefer a 250KB volume with a much smaller treble bleed cap (.0022uF or so) and a 500KA tone with a .047-.068uF cap. This way, the aggressive bite of the SF is retained, if not slightly enhanced, but can also be tamed with a gentle roll back of the tone control, and it can now get a more dubby, deep tonality if rolled waaay down.
However, I tend to just keep the basses mostly stock, until a part goes bad, then I switch it out with the preferred values. This happens rarely, as those older Peaveys have good parts. The exception is parallel stacking tone caps, it's easy to just throw an extra .033 cap on the factory .022uF to get the fatter roll off I like.