alt Hacker NewsThat sounds like the breakeven if you're holding wing geometry constant and want to compare cantilever weight cost to bracing drag cost. The real advantage is in allowing for thinner and higher aspect ratio wings like in the Boeing X-66 which was designed to fly considerably faster than 200mph and make fuel savings.
I guess an additional advantage in this design is that the weight of the batteries is in the fuselage rather than the wing, so additional strengthening of some type may be necessary in either scenario.
I'm terrible at estimating aspect ratios, but the plane in the video doesn't seem to be particularly high aspect ratio. Since they will be presumably holding less fuel, they could certainly be thinner though.
While poking around their website to try and find good still images from a top-down angle of their demonstrator, I did notice that there is no bracing in the concept images of the ES-30, for whatever that is worth.