VA clarification (in General)

I'm not the smartest man around. Just would like to get my interpretation on VA clarified. Not sure If I'm reading it right.

So it says: train to your Most Powerful Blow for maximum efficiency.
VA can be trained even higher than your MPB to counter the effects of Dispel Magic.
Maximum effect would be 40% Life Leaching, or very near it.

So for example, my MPB is 100 so that means VA should be trained at 100 for max effect and would get around a 40hp life leech?

Yes but VA less than 1k usually hurts yourself and less than 10k doesn't reach 40% efficiency. But the general idea is correct.

Based on the naive definition of "efficiency", yes. But remember what the M is for in MPB. What I would actually recommend (and realize that I don't use VA) is training it based on your average blow. The ROI is reduced, and thus there is argument over what "efficient" is.