And does the brazilian fretboard make a difference?
I think you'll get a variety of answers on this. My experience is that
on the right guitar, it can make a difference if you know what to listen for. The caveat is that I suspect that most folks wouldn't notice, but I make my living in the studio, and am a synthesist and sound designer, so maybe I'm simply attuned to this stuff.
And truly, the contribution any guitar wood makes has to be taken in the
gestalt of the entire instrument.
On a great guitar, all things being equal, it seems to allow the note a faster attack and a bit of openness and clarity that IRW seems to - I can't find a better word for this - filter just a touch more. I think IRW is great, just a little warmer sounding. The BRW seems to me a little closer to ebony in the way it has that fast note attack.
Then again, all 3 of my Private Stock electrics have Madagascar rosewood, and they sound wonderful in their own way. My McCarty has the BRW fretboard, as does my '65 Gibson, and I've had a few others from PRS with BRW. I've also had a lot of IRW guitars, and they've got their own thing happening, too.
One thing I'll stress is that I am talking about
very subtle differences. But of course, subtle differences add up, and that's what makes guitars such interesting instruments.