Remember guys, you might have a boiler online anyway, or if it is a brand new installation, why not consider the base LL boiler and have a separate oil or gas boiler?! You could buy an oil or gas boiler new or used for short money and not even have to think about the changeover of fuel types in an emergency. I know everyone wants this to all be in a sweet gift wrapped little package, but that has a price, one that would be far greater than a separate boiler. In the highly unlikely event that a coal unit would fail, having a plan 'B' is admirable, but understand that I have 3 260's running for over 35 years without any oil or gas backup (another coal boiler sits as a reserve) and people live in apts that require heat and hot water 24/7/365.
One other thought, in wiring your controls, we ALWAYS bypass the circulator functions of a 8124 or whatever, and wire the pumps or zone valves to open or start on demand through a Taco controller, regardless or the temp of the boiler. If you lose fire for any reason, you still have circulation, and moving water will not freeze. This is not new, we have done it this way for 40 years. I know it gets just as cold where you live, and copper snaps in a heartbeat if it freezes there also.....just saves the 'emergency nature' of an outfire when it's 10 degrees out.
There are other ways to make your dollar go further, and yes, Dave and Matt can engineer an auto changeover system for fuels, but it is not necessary IMO. It could double the price, and I see no reason for adding the complexity. KISS philosophy works every time. This is not rocket science.