I've got a jap maple fret board neck on one of project basses and it is totally superb equally as good as my two USA P basses.
I also have an Allparts neck, that I have just attached to my latest project, this one is rosewood f/b. Nothing wrong with it at all, frets all level, truss rod works, I did have to do a spot of filing to the nut but that's not exactly an issue. It is good but not the same quality as the jap one, although I can't tell you exactly why not .