You're right about vim, though I tried to avoid keys having different uses in different modes. Earlier I did have transformations positioned with arrow keys, but I found it frustrating switching between that and general movement. There's a tension, the primary mechanic, in that two different shapes can never really be in the same place -- just overlapping to varying degrees -- so the "movement" of choosing the transformation target can't always start in a neutral position so that placing the new shape feels the same as bulk movement. This doesn't seem to be a problem for red zone movement, even though the physics are considerably different, I suppose because you're still directly moving an object (the head of the line).
But yeah, weakest part of the controls is still shape selection. Thank you for playing, and for your thoughtful comment!