seems like a cool idea + would save major $$$ for the big time growers, a guy on another forum said he hasnt broght in any new soil to his garden since before 2000!
I don't compost it but its still there to be used next year. A few organic additives to freshen it up and its almost like brand new. I Do beds so it would be impractical to dig up and make a compost pile. Anything I have potted I usually throw that in the compost.
If its organic soil then by all means recycle it. You can just replenish some organic amendments and re inoculate with a compost tea. If synthetic ferts were used then there might be some salt build up over the course of an entire season.