welcome to the new world of radiant heat let me take a stab at explaining it. first of all it has to be all calculate out. usually the supply house who carries it will do it for you.
radiant heat operates under a temperature usually around 110 degrees. maybe 120 high side this is cost effective B/c your hot heating water too 180 degree like baseboard. its done by laying flex pipe under the floor and covering the whole surface.
there are plates that give off heat and insulation that is required. NOW here is where the cost efficiency gives in. with baseboard first your only heating the outside wall. with 180 degree water. with radiant heat your heating with 110 degree water and your heating the whole area. with out going into detail. it uses less BTU's to heat the floor and have the heat rise, then to heat the the walls and have the heat not only rise but move out to the whole room.
also for more efficiency on new boiler and mixing valves ten could adjust themselves to the outside temp.
for example if its 0 degrees outside you want the water to be hot in your boiler to 180 degree. you may need all of this BTU to heat up your house.
but on a 55 degree cloudy and windy rainy day you may not need 180 degree water you may need only 140 degree water in the boiler to heat up the house. so the boiler does not have to work that hard to heat your house up.
Now the only negative thing I can really come up with is the equipment is kinda on the pricey side. So what I am saying is its not cheap to install. I myself only did a few and I can in as a secondary person. some people get baffled and I am usually the guy who fixes the problem and in and out of the house.
Even if I was to do my own house it would cost a pretty penny for material.
again I will say its not cheap but well worth the comfort level..............
George
one more thing you mention wood being a insulator. once you heat the wood up to 110 degrees the wood maintain that heat for a long period of time so it will give a long heat cycle once its heated. same with concrete once its heated up it will maintain that heat for a long period of time.
and no its not really a do it yourself type job.