Re: Walnut? Light or heavy?
I find walnut somewhat harsh/brittle. I had a Gibson Firebrand SG years ago with an ebony fretboard (that rather rubbery sort of ebony)-- very stiff sounding, little resonance; no matter what pickup I placed in it, the wood would essentially dictate the overall character of the output emphasing only the harsh tones of the pickup. Useless in the studio. Good sustain, though. The Gibson V II made between '79-'82 had the same problems in my opinion-- laminated maple and walnut--less sustain due to the design.
Darker than maple, but not as warm.
Now, in a bass guitar, walnut is nice in conjunction with maple! Different expectations in regard to tone I suppose-- emphasis on a clean sustain.
Just my take...