I have been going round and round on this subject for the last year or so. Currently in the design phase of a house for my folks and obviously the heating system controls a lot of design aspects.
Construction will be 2x6 with sprayed in cellulose in voids. Then 2-3 inches of recycled 4x8 Poly Iso (sealing all gaps, cracks) then 1x strapping (vertical) 2ft o.c. then lap siding. Similar detail on vaulted ceilings and close attention to foundation insulating and this should be a house in the 10 to 12 btu/sq ft at design(0 deg F for us). R-3 Windows really stand out now in the heat loss calc but it gets hard to justify jumping up to triple panes when it means lots more money to burn a tiny bit less wood a year.
Solar thermal heating is the ultimate but when you start crunching the numbers(btus and $$$)it can get out of hand real quick.
Wood is the fuel source for us as we live on 72 acres of mostly wooded land and have always heated with wood. Now, to do it with maximum efficiency, comfort and convenience.
Masonry heaters are very appealing in a lot of ways. No power needed, High aesthetic value, efficient, comfy radiant heat, convenience of one or maybe two fires a day. From discussions with a couple of friends with MH they get a bit harder to control in the shoulder season as you are building fires based on conditions that are 12 to 24 hours away. This makes overshooting or undershooting a reality at times. Still they like the MH a lot but might do things different if starting over. Also parts of the houses that just don't get as much heat as they want and these are open house layouts.
Masonry boilers were discussed earlier. Check this out if you haven't seen it, its pretty cool:
http://heatkit.com/html/lopezs.htm
Of course now your adding electrical requirements and negating one of the big advantages of the masonry heater. But now you can get more heat to the extremities of the house(Bathrooms!).
IMO the gassifyer+storage+low temp emitters comes out ahead in the end for efficiency, comfort and convenience. Like a masonry heater it is a high mass heating system but one where you can put the heat where you want it, when you want it. Plus DHW year round.
Man, I can't wait to get my Varmebaronen and storage set up. Probably about the spring time
Noah