Only if a conventional boiler or other heating sources are used, not a
modulating condensing boiler.

I'd want to see further testing evidence for this, either way. I'm not
convinced which is more efficient.

Basically, does the higher temperature burn required to reheat the heat bank
outweigh the fact that the boiler gets to do occassional full power burns,
rather than cycling, or modulating low.

Remember, that the heat bank might still be providing a reasonably low
return temperature with a very high flow/return differential, which should
offset some of the problems with regard to condensing.

Christian.