I'm told by uncertain sources ("h - u - b - b - y") that he thinks Ebony's colorations won't have anything to do with density or wear characteristics.
He pulled out one of the older Fender Strats with a maple fingerboard - 30 years old, it has dimples and wear-bowls at certain places, but so do the frets. It's perfect for what it does. The same aged acoustics - with ebony fretboards - don't show as significant wear despite having larger gauge strings (ie, a better 'sanding' effect).
He pointed out "some guitar owners replace fretboards - those are just thin veneers over the neck. Luthiers do that easily enough."
In short, "If nicely marbled ebony lasted only half as long and started splintering, so? Just replace it. Get another 10 years out of a new piece. The frets probably need replacing anyway."
I still can't believe that anyone who loves Wood Anything doesn't love all kinds of grains and all kinds of patterns and colorations. I'd be fascinated to meet guitar players who'd turn their nose up at any instrument with More Wood Patterning than Less, but apparently some guitar-makers believe this has always been the case.
Oh... one other correction... the comments about "looking at guitars" was more related to a Purchase Decision based solely on The Looks, as if I'd be hanging them on a wall instead of playing them. Some instruments are indeed guilded like museum pieces (I really don't like mother-of-pearl inlays - there are fingerboards that look like NASCAR racers!). Just give me an occasional dot or stripe. Ah, yes... 5th Fret... now the 13th...