You're probably right about boosters being too hard to dodge. It was the last thing I added and didn't have a proper amount of time to playtest and tweak it. I could probably reduce the speed slightly but would rather spread the boosters a little more so the gaps would be easier to fit into.
As for the walls, I was thinking more in the way of increasing the damage applied from the hit. I wouldn't want to drop this feature altogether, because it is the main mean of deceleration in the game ;)