Hi Dharma Bum,
I applied to DMA programs in composition last year and I assure you that they don't care about GRE's. I talked to several faculty members of the universities which I applied to (Northwestern, Stanford, Columbia, UCSD) and they all said that GRE's are not important. In fact, I got a similar score to yours and I got into where I wanted to go. That said, it is extremely important that you focus on your music. Music, music, music. Send them great scores with great recordings, and write an statement of purpose that talks about your music.
Don't write some autobiography because they are boring. Write about your music, your thoughts, your musical interests, etc. This is what they care about. They want to know about your artistry and not your diplomas, GRE's, etc.
So, here's my advice: focus on the music and write an essay that speaks about your music in depth (so don't say: I like this, I don't like this). You need to explain why you do what you do in depth.