I was going to invest in the WL-110 but the $7,000.00 price stopped me. If I remember correctly the unit only has 12 gallons in the steam chest of the boiler so you have to factor that in for your heating load and domestic hot water needs as well.
Going from my memory here:
The WL-110's hot water vessel is made by Axeman Anderson.
The flue breech for the stove pipe stack comes right off the top if I remember correctly and the unit is very easy to to clean in the off season by removing the gasketed covers to scrub the
heat exchanger from what I remember reading of it as well as removing the hopper and stoker to clean them in the off season.
The information on the LL web site is very well explained and shows everything about the WL-110 and the options it has.
Having a pressure tested hot water storage tank rated for hydronic heating would help you as you could insulate it and provide more hot water for heating the home and its Domestic Hot Water use.
Adding a fifty gallon upright tank would create 62 gallons of hot water for the heating loop and the Domestic Hot Water without investing in a larger boiler.
You will want to have several extra ash baskets on hand so you can change them over several days if needed and be sure to shake down the ash basket to level off the coal ash in the ash basket
As far as the change over from coal to oil and back to coal its fairly easy and Matt has it well explained in the owners manual. The WL-110 requires removing firebrick to install the oil burner and a few other small jobs to bring it back to oil quickly, BUT there is no working on it while its hot!!!!
The WL-110has an oil burner holder on the boiler frame to set the complete oil burner and its feed oil hose in and set it aside while burning coal where the oil or gas burners fire tube tube is pushed through a piece of steel on a hinge with round hole the size of the burner tube and it lets you swing it out of the way for storing it while coal is being burned.
I hope that I have helped you with your inquiry