Are you going to back up the wood boiler with a completley separate oil/propane furnace?? Your post dosn't mention this. If so, it would be alot more cost effective to just buy a wood boiler that already has the oil/propane backup right on the boiler itself. I recently built my house also and if you are like I was its all about saving money where you can..
Have you looked at the AHS boiler? I have the AHS multifuel ( wood/coal/oil ) and I love it. The oil only kicks on when the fire dies down. That way you are not a slave to the boiler... I had a wood eating OWB and thankfully I found someone to buy it. I put my AHS inside my garage and it is WAY,WAY more efficient than the OWB was.
I looked at the Tarm but it didn't burn coal. I then looked at the New Horizon. It looks like a very good unit but they didn't offer the automatic oil backup. They might now but didn't last year when I was looking at them.
I also looked at the Royall indoor coal boiler but there again no oil backup.
I went with AHS for two reasons the first is the customer service is just simply outstanding. The owner (Jeff) answered my questions for a good half hour during my initial call. and I have probably called him 4-5 times since about little things and he is just great about it.
Also, when i called him initially, I was prepared for the usual rhetoric from a dealer/salesman about outragous burn times and how much more efficient superior their unit is compared to others ,,, you know the deal.. Well, he was totally honest about burn times and did not try to B.S. me into buying his unit.
Secondly, and this is a important feature with opil backup, The oil burning chamber is a separate chamber from the wood chamber. That way the fly ash doesn't plug up the oil burner. I believe AHS is the only one that has this feature. ( if you look at the pic on the website of the multifuel boiler the oil chamber is the round part on the back)
SO, to "Boil" it down I would highly recommend AHS. Also have you looked into a Gasifier unit. They work great if you are going to burn wood only. My co worker has the AHS gasifier " woodgun" and he loves it. It is pricy but not as pricy as Tarms gasifier and it will take much larger pieces of wood then the tarm.. I wanted to burn coal so I went with the multifuel..
http://www.alternateheatingsystems.com/
I hope this helps you out...
Shawn,