Bottom line is that plane was evacuated with no loss of life, just like the "miracle on the Hudson" a few years ago. Where is the evidence for the delays of which you speak? - the footage of people wheeling luggage?

I have not had to evacuate a plane quickly, but I would almost surely grab the small backpack that I stow underneath the seat in front of me. It contains a small FAK and other items that might come in handy. Would I bother to open an overhead compartment? - probably not, but I might consider it if I could do so without delaying anyone's evacuation. Action would depend upon circumstances.

In any case, I would try to expedite the evacuation and assist anyone who was losing their grip....