+1
The top end response of those two wood combinations are interesting, and it really is a matter of semantics (i.e., how do you define 'bright').
The alder/RW (especially the NYC 'true rosewood' models) actually seem to have a bit of dip in the upper mids, resulting in some 'space' between the mids and the treble (like some bass cabs). This results in the basses not sounding 'bright' through the upper mids and lower treble, but rather full and fat down low, and a bit sizzly up top, with that upper treble sitting out there by its lonesome (especially with the somewhat scooped voicing of the stock HC pickups).
Ash/maple has a real bump in that 'ganky' 1K to 2K area to my ear, making those basses sound 'bright' (i.e., grindy and very present in the upper mids), which masks the sizzle a bit.
So, depending on how you define 'bright' (i.e., aggressive upper mids, or extended high treble), they both can be!
My alder/Madagascar RW Sadowksy JJ was among the sizzliest basses I've ever owned. My ash/maple with Sadowsky singles is much more punchy, and the combination of the punchier singles through the mids and that maple board make it growl and snarl versus the 'warm, smooth with sizzle' voicing of the alder/RW.
IMO... hard to talk about this stuff in general terms sometimes