Battery Test Centre, page-4

Not particularly.

The DC-DC efficiency is about 80%, the rest will be balance-of-system losses (i.e. normal/typical regardless of battery type).

The point is this - in the modern world there's no shortage of solar input available in most cases - so putting (say) 12kWh in to get 10kWh isn't an issue in installations for which our battery is appropriate.

What is the real win is being able to get that 10kWh out each time - 100% down to 0% - every time. No reserved capacity, no issue with complete discharge.