Well, even if the shutdown option wouldn't save money, one could advertise with "green hosting", what would be another plus for PR and image.
I haven't contacted them yet, but I think I'm gonna do that soon, since it doesn't seem anyone has more than testing experience with it. On Google I've also only found people who tried it and were like "wow", but no real case studies. There was cover article about it in a german Linux mag 2 months ago, but they also didn't do more than a small test setup with NFS and VMware. Would be much appreciated, if you can post a review, after you've tested the trial. It's not that urgent, at the time I'm only working as service provider, a hosting company is planned in ~4 months, so there is enough time.