I may be overlooking something, but I'd certainly consider Robin's estimate of 1-2 week doublings a FOOM. Is that really a big difference compared with Eliezer's estimates?

I think Eliezer estimates 1-2 week until game over. An intelligence that has undeniable, unassailable dominance over the planet. This makes economic measures output almost meaningless.

Maybe the point in contention is not the time it takes for super-intelligence to surpass human ability, but the local vs. global nature of the singularity event; the local event taking place in some lab, and the global event taking place in a distributed fashion among different corporations, hobbyists, and/or governments through market mediated participation.

I think you're right on the mark with this one.

Even this difference isn't that great, since there will be some participants in the global scenario with much greater contributions and may seem very similar to the local scenario

My thinking diverges with yours here. The global scenario gives a fundamentally different outcome than a local event. If participation is market mediated then the influence is determined by typical competitive forces. Whereas a local foom gives a singularity and full control to whatever the effective utility function is embedded in the machine, as opposed to a rapid degeneration into a hardscrapple hell. More directly in the local scenario that Eliezer predicts outside contributions stop once 'foom' starts. Nobody else's help is needed. Except, of course, as cats paws while bootstrapping.