Rosewood neck sounds like an awesome idea dude.
HOWEVER, a few things I now about rosewood.
1) it's a bit difficult to find. Over-logging has made it increasingly rare and more regulated (See Gibson).
2) Because it's rare, it's also pretty damn expensive.
3) It's also difficult, I believe, to find enough wood to make a neck out of.
4) Rosewood is like, really dark sounding. No, I mean, like a Goth chick reading poetry in a Dungeon while drinking blood dark. If this guitar is going to be neck thru, it'll probably have less treble than an Electric Wizard record.
5) I love rosewood. It's dark, but it's warm. It's the most popular fretboard wood for a reason, and if you can find enough wood to make a neck, and afford it at that, and you don't mind a (really) dark sounding guitar, I'd totally go for it, because it will be cool as shit.