I have had the opportunity to run my unit for 5 days straight. I've been watching it as I would have watched a small child playing in the backyard. Outside temps have not been to the standards of "winter", yet it has been cool enough to justify operation. Only using the front half of the available 74 sq ft, I have got 24 hour burn times. In the morning when I turn up the thermostat it generally generates a burn at the OWB. In less than 30 minutes the water is back up to 185F and the damper is closed again.
I read alot about the issue of the classics smoking. Well I'm here to tell you when it's in operation it smokes less than a chimney on a house. When the water gets up to 185F and the damper closes, there is only a whisper of smoke that evaporates within 4' of the unit. If it is a long time between the burn times, I would think it's out of wood if it wasn't for the fact my remote temp sensor tells me the water is still between 175-185F.
I guess what I'm trying to say is smoking really depends on what you burn in it. Well seasoned wood (which I use) must be the key to how much it smokes.
In short, I feel this was a very good investment for us. Adding the DHWX after the intial install from our dealer was a bonus. My payback won't be as quick as those of you that use gas or heating oil to heat your homes, but the convienance of not hauling the firewood into our home to stock an indoor woodburner is worth it, as now we can keep our home cleaner, not having to stock the fire every 4-6 hours.
One additional note: I'm located at 2000 ft on top of a ridge and my nearest neighbor is 1/4 mile away. Check with CB about your installation site. You may require additional chimney sections.