I went back and forth on the stat boost thing, but decided it added a good sense of "hey this is an epic spell now" to it. Feel free to disregard.
And I stuck the "subject to GM approval" in to account for GMs who don't want the players to have access to every race. EDIT: and it occurs to me that if the limitation is "you can't change your type", and my type is outsider (native) because I'm, say, a sylph, then I could reincarnate as a Janni (still a native outsider) and get a fly speed with perfect maneuverability, plus bunch of spell like abilities. So I think limiting it to 0-hd races make sense.
In my own campaign, it looks like this is primarily going to be used as a rite of passage -- the PC has just taken the Divine Source ability and started granting spells to followers, and the player wanted to reincarnate each new worshipper as a kind of initiation. Yeah, that'll get expensive, but the flavor is awesome.