Interesting you put it that way because I've basically combined both techniques into one practice. In effect it's circular.

Work as Witness is, for all intents and purpose, resting in awareness, much like do-nothing meditation. The doer of work is simply another form in that field of awareness. And since that's the Atman and Atman is Brahman, Work for God is approaching everything as God, for God and in service of God so that completes the circle, so to speak.

Another way to think of it is the One manifests into the many and experiences itself through the many. So the above approach honors that purpose.

The Work as Witness aspect also dovetails nicely with and reinforces my do-nothing meditation practice, much like informal mindfulness practices throughout the day reinforces a formal mindfulness meditation practice.