Shaving down to 512MB?

I've been using a 512MB SD card for my Project M needs for quite awhile. However, the unzipped files have gotten too large. Is there something "non-essential" that I can delete and still run it fairly well? Yes, I know I should probably get a larger SD card.

Also...am I supposed to overwrite the full zip files with the new launcher files? The downloads page doesn't make this clear.

Thanks for any help guys!