For one, the spider surfaces. Right now it uses the boost button to also stick to them. It always feels a bit jarring that you have to wait until you're fully on the surface before you can latch to it, otherwise you boost, which can lower your speed if you're going fast. Having a separate button that you could hold as you approach would do wonders for making this action more fluid. Besides, they don't seem like two actions that would be on the same key, while the down/crouch button would fit much better.
Also, it would be nice if you could stick to them without looking down, especially because you generally have to look back up when you jump off anyway. Perhaps 30 degrees extra either way.
The other bind is the one that changes the multi-cannon mode. It seems awkward that it has you press the select button again. For those of us who use mousewheel to select, it's even more awkward. This would work a lot better with a button like middle mouse click or even taking over the alt fire and remove zooming/manual overheating.