I don't believe the Central boiler will do very good with coal. It might work to mix it with wood but probably won't burn real well.
I didn't go look it up but if I remember right the Heatmaster 5000E has an extra bypass to pull more heat out of the wood. That to me sounds like you would want to avoid green wood completely as it would be cooling the smoke a lot more and cause creosote problems.
A few other things I will throw out there that you may already know. Heatmasters are imported from Canada and made from 409ss. I personally would never buy a boiler (again
) that was made of any type stainless. Doing a search will get you plenty on info from both sides.
Central boiler has natural draft instead of forced draft and I don't think they have an ash pan option so you will have to shovel the ashes out the door. Central Boiler does have an optional blower that can be added but from what I have heard they don't work very well because the boiler was not designed for it.
You might want to try looking up Scott7m on here. I haven't seen him post in a while but he was from Grayson Ky (not sure if that is close to you) and he sells the same brand as me. Just another option worth looking at.