I'm not sure what your asking coolidge, if you mean wood usage, perhaps 20-30% more wood in the B-L than the 250 and the 250 will burn about 40-50% less than my old Wood Doctor, personally I like the simplicity and the ability to burn the less desirable woods in the B-L, I also as a service guy, like the ability to easily split the boiler in half for any future repairs, the low water volume and high refractory mass on the B-L are also a big plus. Don't get me wrong, the Optimizer 250 is a great boiler in my opinion, it will burn those undesirable woods but as you know, the maintenance on it is more time consuming than the conventional's, They both have their place, Have you had a look at the B-L up close, if not, then Please stop by, I have 2 of the 28-40's out front, they are both the Coal shakers.