Charlie,
I don't want to hijack the geothermal thread too much and since I'm mostly in the commercial world, I don't have as much first hand experience with the premium residential oil boilers as I probably should. That being said, the Viessmann and Buderus (European) brands are very popular with high end residential contractors. They've really refined the design of their cast iron boilers to optimize efficiency and they combine their boilers and burners with very sophisticated controls to adjust the heating water supply temperature as the outdoor air temperature changes. The downside to this can be a limited contractor pool and expensive proprietary parts when service is required. For the rest of us, it's hard to beat a properly sized Weil McLain boiler with a Beckett oil burner. Any certified oil burner tech should be able to work on one and parts are readily available. Stay warm during "snowmageddon"
