I'm waiting for an E-bike designed for experienced cyclists who only want to flatten some hills, or get some extra help in stop and go conditions. So far most of the offerings are designed around riders who really depend on them, and so the battery is too large and heavy negating the benefit.

A unit that could provide an electric afterburner for hill climbs or a bit more speed on long grades could be built around short run times, and possibly some regeneration on descents could use a much smaller battery and motor keeping the overall weight closer to that of a normal bike.