I worked on a job where we used horizontal nailers and spray foam on a building and it worked great. Didn't need vapor barrier, as the foam is the barrier, really tight building now. Got the idea from a timber-framing friend. They hung the drywall on the posts, put horizontal studs on, screwed drywall to the studs, wired the place and foamed right over the wiring after inspection. Much like in the horizontal nailer system in Tedd Benson's 'The Timber-Frame Home' but with the added efficiency of spray foam.
Mark