My supply house told me the same thing. They had six sitting there and all but one buyer wanted coal grates. They have been sold and installed and they are having good reports coming back. When oil went below 2.00/gallon this spring, lots of folks bought another 330 tank and topped off. Can't blame them, but I wouldn't bank on that happening again.
I looked over the boilers as I use a few Biasi 3 pass boilers from QHT. I'm impressed, and the efficiency number on dry wood look remarkable. Coal is a no-brainer to me, however. You can have your cake, and eat it too with this boiler.