Remember it is the bark, not the wood that is used. Balsam fir bark is smooth and relatively thin, and the trees don't get that big so the bark doesn't build up like larger growing trees. I think just about any other conifer bark would be better. Although Balsam fir and Douglas fir are both called firs as common names, only the Balsam is a true fir. The Douglas fir is very different and not closely related to Balsam firs at all.
