I installed a Classic from Cetral Boiler last fall and couldn't be happier. My dealer was very knowledgable and the few questions he couldn't answer were handled quickly by the factory. I researched all of the brands available to me locally and was most impressed with the CB quality and support.
Burn times vary greatly. In the winter, I use mine to heat my house with forced hot air, barn with radiant in the slab and domestic hot water. I keep it going in the summer for DHW. I have gotten burn times as long as 3 days in 30-40 degree weather with the firebox stuffed full of seasoned hard wood, but when it drops down below freezing night and day I have to feed it twice a day. So far this summer I've been feeding it every 3-4 days for DHW. Proper seasoning seems to give a lot more heat.
I was concerned about having enough hot water using the side-arm heat exchanger (2 kids and a wife who does laundry every day) but I have never had a problem. I have the circuit breaker for the electric water heater shut off and haven't used it since I fired up the furnace.
You do have to like making firewood. I haven't measured how much wood I've been using, but it's been a lot.