Rick - clearly said. I think we may have be in complete agreement, which is odd for the internet.
I stand corrected on the Poisson vs Gaussian nature of the photon noise, but I suspect the central limit theorem will rear its head when the flux goes up to reasonable numbers. Either way, stacking and integrating are the only tools we've got to attack noise.
I've ended up with 10 minute subs for precisely the reasons you outline, the most significant of which seems to be the level of polar alignment I can get with the PAS on my G11 @ 530mm fl. Lazy me.
cheers,
Andrew.