A while back I listed two almost identical sopranos on eBay....one with a rosewood fret board and the other in baked maple the maple one didn't attract as many bidders as the rosewood...if I hadn't put "maple" in the description no one would have known the difference.
From a (newish) players and buyers perspective I don't have fixed ideas about which wood should be used but rather am/are looking for something that is fit for purpose and which will retain appropriate value to me and others. Bruko use maple for their neck and fretboard combination on their No 6 model and it doesn't seem to put people off of buying them, and there is a vintage Kamaka on eBay.co at the moment that also doesn't (to my eyes) have a separate fretboard. Similarly some pictures that I see on the web of Nunes Ukuleles seem, to my eyes, to show no separate fretboard. There will, of course, be many good reasons for having a separate fretboard, but that arrangement doesn't seem to be absolutely essential.
The colour of a fretboard currently matters to me, but my particular eyes are no longer young and being able to more readily see strings and frets is a help. By way of example I'd like a Flea but perhaps black strings, black frets and black fret board might be an issue in use, would I need or welcome more colour contrast? Similarly are clear and light coloured strings less visible against Bruko's light (coloured) maple fretboard?
Thinking about Ken's Ukes I, as a buyer, see his product(s) as a true to original replica of an early Martin and that authenticity has value to both me and those who buy them second hand: retained value is an issue. By using a product other than Rosewood the authenticity is, in my mind at least, brought into question and so is the resale value. IMHO the very high quality of Ken's products, regardless of which wood that he as a skilled luthier chooses to use, is beyond question. However, and again IMHO, quality and (financial) value are not the same. I hope that Ken is able to find a way forward such that his many wonderful and classic replica products will, in some suitable form, be available to us - IMHO it doesn't always have to be a Martin replica, there are other valued designs too and commissions.
I hope that, despite my relative ignorance, my view of the situation is helpful.