While I think the conceivability argument for property dualism (the "zombie" argument) is ultimately sound, I don't think the same considerations apply to the conceivability argument for substance dualism (the "disembodiment" argument), for reasons I discuss here. I also think that using "I" in arguments like these is problematic: "I" is an indexical with no determinant referent, so whether or not disembodiment is conceivable depends on whether or not "I" refers to my body (which cannot be known a priori, since "I" ultimately refers to whatever I happen to end up being), so the argument begs the question. I think the most effective way to move from property dualism to substance dualism is to argue from the incoherence of attributing mental properties to composite material substances, as I have done here.
Your argument for substance dualism seems akin to Victor Reppert's. Is that a fair assessment?
I'm not sure what Victor Reppert's argument is, so I can't really say :P
Wouldn't this argument just be against mind/brain identity theory? I.e., functionalism could still be true even if this argument is sound.
Since we're talking about the mind, and not mental states, I think the argument would rule out functionalism. I could be wrong, though. Philosophy of mind intrigues me, but it's not my area of expertise.