That 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.