Looks like 15-18 hours max from people who actually own the big 5100. This from a hybrid stove with a huge 4.4 CF firebox and a lame 8" flue requirement.
Well I have 7 5100s out so far and most of those people are easily getting 20 hours or more when shut all the way down with hardwood. But even if we go with your 15-18 hour figure that is still a whole lot longer than overnight. And as far as the 8" goes the king has the same 8" as well as the buck 91. I only have installed 2 3500s and those where recent so i haven't had feedback on them yet. Yes Blaze Kings are great stoves but there are allot of other good stoves out there.
I totally agree about your statement of radiant versus convective though. I think that argument is overblown as well.