Mark,
Hard acceleration can be deleterious to any lithium pack, including the LEAF. The culprit is heat.
When you accelerate hard, huge currents flow through your pack and, depending upon the cell chemistry, and its internal resistance, heat is generated from this current flow. This heat can degrade the cell contents over time.
I'm very conservative in our LEAF, as we want to get maximum lifetime out of our battery pack. I have only really 'floored it' a couple times, just to know what it's capable of.
The LEAF has taught us to drive much more slowly than before, for the most part.
Lithium cells inherently lose roughly 1.5-2% capacity per year, and I want to minimize any further losses.