As I understand it, the F9 first stage can't actually hover because a single engine at the lowest setting gives the overall stage a TWR > 1. Thus the "hoversla

As I understand it, the F9 first stage can't actually hover because a single engine at the lowest setting gives the overall stage a TWR > 1. Thus the "hoverslam" - they calculate the landing burn such that the stage reaches 0 velocity and 0 altitude (from the pad) at the same instant. But this means the only margin for error is in the landing legs, and they've had some hard landings. I was originally thinking about solid rockets in context of a parachute system, but the more I think about the more I believe truly gentle landings aren't really a feature of the current design. I'm not sure how much weight it would add, but it seems like having the ability to fine-tune the thrust at the very end would allow them to land much more gently and feel better about not introducing metal fatigue or other damage. Of course the addition of a smaller LF engine probably makes the most sense.