I would agree that get the biggest one you can afford because if you ever add on you still can. I installed the 6048 this past fall on my 4500 sq ft home that is 100 years old and I am very glad that I did not go smaller.
i don't know about a tax exempt issue.....but i did write it off under the new energy write off sponsored by the federal govt. for my taxes last year....i am up in flemington area....so was my dealer
Good luck with that audit. The federal tax incentive is for energy efficient upgrades, OWB hardly qualifies, I know I have one.
i was referring to capital improvements