You are adding complexity with this scheme, not reducing it. Multiple DC-DC conversions can't be as efficient as one AC-DC conversion and, as you pointed out, you still have the AC-DC conversion. The DC-DC converter has an AC intermediary anyway. It was also pointed out up thread, interrupting big DC loads is a lot harder than AC since there is no zero crossing to put the fire out. I predict this is a fad that will never really catch on.
