[gumby]

Having worked in this sector I agree with everything you write, though I would add some qualifications:

For grid scale storage, kWh/kg and kwh/m3 (actually j/g and j/m^3) are, for all intents and purposes, irrelevant -- people aren't carrying power plants around, and grid scale investment is the classic Cap Ex/Op ex carry trade.

Also your $/kWh is an input to LCoS rather than a metric that can be used to make a judgement on its own; discouragingly, though LCoS is even mentioned in the article, it's only in a wavy.