Honestly, if you ask me, SpacePan is about how good of a stereo listening environment you have (or how well do you understand headphones, I don't), more than how good you are.

I have two environments, and in one of them I just couldn't get past 40 because of the reflections and everything.

It's more gaming skills than audio. I use headphones (not bluetooth! Too slow...) and work with both hands by shooting with space bar. I think using both hands improve the reflexes and precision.

Well, @Jazzy Tea, my worst scores have been on headphones because I'm just not used to hearing the panning in headphones.

It feels really hard to figure out the position of the aliens when they're not dead center or hard left or hard right. That's what I meant with being used to headphones :D

Jazzy is right. Being in this leaderboards doesn't necessarily mean you're better at listening to frequencies or panning than the rest, it means you're fast with the mouse, keyboard, reflexes... Gaming skills, definitely.