Honestly, l never measured moisture content. If it seems dry enough to burn l will burn it. Its air dry firewood.
As for performance, l found moisture isnt as important as wood type and shape. I dont see much difference with my last years chunks or the ones l chunked green a week ago.
BUT! There is a enormous difference in wood type. Best are spruce limbs and beech. I think the reason is in the charcoal. Spruce limbs produce fluffy flakey charcoal, wery hot and reactive while wery breathable. This is what we want in a gasifier.
I allso found out that water in a engine is not problematic in terms of performance, if it is liquid. Water vapour however, is. Experianced this for the last month when we had 37c and the cooler is too hot to condense any water.