Yep
The MC matters for two reasons. One, if you're weighing water, it has no heat content to release in combustion, and secondly, it robs your combustion cycle of heat, because you have to vaporize it and send it up the stack as steam. So, what are we comparing? We have to quote pounds of wood, at a specific MC. Not everyone has a moisture meter. Telling me you're burning oak you cut last spring doesn't help, because
- did you split it immediately? How small? Is it piled in a mountain(surface gets rained on, center of stack sees no airflow), row-stacked in the open(better airflow, but gets rained on, so MC isn't consistent), in the open under a tarp(is the tarp preventing airflow), in the open under a waterproof roof, no walls(ideal, gets airflow, no rain), in an open shed that's surrounded by forest(poorer airflow, but pretty good drying), or in a closed shed (hasn't dried nearly as well, no airflow; could even be growing fungus).
So you see, it's pretty hard to have a standard unless we all have a moisture meter.
Re Species BTUs - source? "Grampa told me" won't do. I can't find it on the web (at least not in a useful tabular or graphic form, just a few species of softwood in Idaho which by the way vary quite a bit), but I'm not looking as hard as you should be, as you made the statement. I'm not being a PITA here, I'd like to see the data. I'm willing to say I'm wrong, but not just because you say so...