I use all extra credit opportunities offered if the professor explicitly states he doesn't curve. I took a course where the only grades were three tests and an essay. I ended up getting a 91 without the EC... and the EC was a 900-word essay worth 2 points on your final grade.
I wrote that bitch in 15 minutes, turned it in, and got my A.
I'd write the short essay since I'm good at writing papers/pulling shit out of my ass. Even if the professor docks, it's still worth something (assuming it doesn't penalize your grade).