Will it have the same harsh timing requirements as the 2D games? You say she can basically hover indefinately, but the correct phrase is she can theoretically hover indefinately, because in fact, it is very difficult to pull off, unless you can find a nice, inert wall to hover beside.

Also, why does there need to be multi-jump for the screw attack? In Metroid II, the screw attack was just as deadly without spacejump; the only real reason the two needed to go together was to escape the un-screw-attackable metroids, speaking of which, will you still be invulnerable while screw-attacking?