What are your opinions?
I can't comment on the specifics of the state table design - would have to leave that to Henri. However, anything that increases modularity is a good thing. I'm in favor of the overall direction to break up the pipeline into component stages. Smaller components are more easy to manage - specifically in your case this should allow separate backends to be chosen per pipeline stage.
It seems reasonable that these changes would be deferred until after 1.0.
Ivan