Hm, just thought I'd bump this back up and compare and see if you've revised it at all...
Edit: Okay, doesn't look like it.
On reflection, I have to say, this spell is a little over the top even for a sorcerer or wizard spell. Let's see- it makes you immune to almost everything, gives you fantastic mobility, and inflicts about as much damage as a meteor swarm, but it's force damage, so virtually impossible to resist. Hmm.
I'd say that the movement/incorporeal/immune to any sort of harm stuff alone is worth a 9th level spell- it's roughly a variant of astral spell, minus the plane travel part, only without the vulnerability to having your silver cord cut.
What happens if your projection is destroyed? Right now it's kind of a cheap way of doubling your hp and then going off to wollop someone in the next room for 25d6 damage, no save or resistance.
Sooo... it's presently a lot like an astral spell + meteor swarm without a save + Tenser's transformation. I see no real drawbacks- the helpless body thing isn't really a drawback, since any 17th-level or higher caster is going to ward their body heavily before casting it (especially since they can't cast other spells from their projection).
So on reflection, I'd definitely tone it down a lot.
