Outdoor wood boilers are good if you are trying to clear-cut a forest and quickly dispose of the wood, but that is about it. My house used to be heated with a wood boiler also, but mine was inside. I replaced it with an EFM and wished I had done it sooner. With the high btu content of anthracite and efficiency of the boiler, it now costs me less to heat the home with anthracite than wood. I also get to skip the smoke, creosote, bugs, and 2 am reloads.
I still feed my EFM out of a drum...not a big deal to top it off when I go down to take out the ashes.