Plans are changing in the Knapp household eh? I thought this addition was only 1200 sq ft like last week lol. I do agree the biomass boiler would be awesome in terms of "set it and forget it", and I know a local guy here that picked up several semi loads of old seed for pennies on the dollar to run through his biomass unit which worked out fantastic for him with no thermal storage. This was Tarm units in tandem. If you stay closer to the 5,000 sq ft area you're really open to anything you want IMO, any regular gasser or HE conventional wouldn't be a total time waster feeding it all the time. Head toward 10,000 though and it limits your options a bit. A BL 34-44 may be a little small for the application, as it's a similiar output to my C375 but holds a lot less water. Perhaps consider a C500 in that event? I'm not sure if you've ever played with a BL Dylan, but I suggest you do before pulling any triggers. I'm not familiar with the gassers as you know, so I cannot comment on the EGR or G3 in terms of experience but the G3 is far too small on paper for 10k ft, and pushing it hard at 5k with only 140k btu output. The EGR isn't much better and another G200 may struggle pretty hard at 10k (again, just on paper). I know the aforementioned biomass guy swapped out to a G400 at his new place, which I believe was around 7500 sq ft and it seemed to handle it decent but had a hard time keeping a 12 hour burn if I remember right. Log house though, not very well insulated. I know my C375 would feed 10,000 ft of well insulated radiant easily for 12 hours, but not on a wheelbarrow full lol. Overall square footage you settle on will be a large deciding factor on what's most practical for you IMO. BTW my price for the radiant goes down quite a bit over 6,000 sq ft haha