I have had one in my house for about 12 years. No major problems.

Some things to keep in mind though.

The internal boards will fry if lightning strikes near your house have
good surge suppression on you house.

Have the installer give you the emergency board so the system will
operate as a normal boiler if the board goes bad.

Have the system cleaned regularly

Are you going to use a chimney or use the power vent kit? If you use
the power vent kit make certain that the power vent is in a location
where it does not trap heat. Had to replace the blower once due to
this.

The zone valves sometimes stick in the open position, ask your
installer to add the proper lubricant additive to the boiler water.

Funny thing is that our oil supplier was the one who recommended the
system, now they don't sell this as it does save oil use. We went from
2000 gal to about 1800 gal of oil used per year for our house. This
includes domestic hot water as well.