About the new slider in the game. I don't use the cultural slideer ever, and if I do, I very rarely go over 10%. I can also run my research slider at 80% in the late game. I'm afraid though, that If I do take commerce out of research and put it into espianoge, that the AI won't do the same and I will fall behind in science.

And also, what happenes to SE civs that don't have much to put to commerce? As I understand it, the more commerce going into espianoge, the more espionage points you get, but what happenes when you don't have much commerce to begin with?

They mentioned on Friday that buildings and specialists can grant espionage points so SE's aren't necessarily left behind.
As to the usefulness of the slider, well, we'll see what strategies develop. I'm sure pretty much no one runs their cultural slider at 50+% for very long (barring an eminent cultural win), but I sometimes run it high for a few turns to pop borders on a small city, or low for awhile to help in a border dispute.
Espionage will probably end up being similar; maybe you need a few more points for a mission or some effect, you up the slider for 2-3 turns to get an edge, or leave it low for a longer period.