Might work fine but probably a number of factors.
Availability, the nursery I have bought thousands of spruce from lists several types of firs but not concolor
Pricing, the firs are generally a little higher priced than spruce. Maybe just a volume thing for that grower.
Growth rate, concolor is listed slow to med growth
Deer munchy factor, firs are likely to be browsed more than something like white spruce
So adding some into a small planting is maybe a consideration but anything large scale has a lot of little negatives that add up especially in the pocket book.