Aw thanks Ross! (≧▽≦)/
I was hoping if one keypress turned you 45 degrees and you always moved in one of 8 precise directions, you could do stuff like double-tap to quickly apply a new velocity at 90 degrees, or triple-tap a direction to make a very hard turn. Possibly this would let you move around more responsively because you can always be certain of what velocities your inputs will result in. The main motivation for this was I had a lot of difficulty with navigating around the two electric gates where the first enemy appears the last time I played.
I put more time in and tried shooting with the repairbot this time, I see why you would want to preserve finer rotation. It might be sufficient to add a modifier key which allows you to rotate 2x as fast while it's held?
About the animation, I'd personally avoid adding more rotation sprites since pixel art suffers outside the 8 major rotations, even if it results in some ambiguity about the stored rotation ^^;