tmpfs, ramfs, memfs

Anybody have any data comparing tmpfs, ramfs, and other ramdisk like
filesystems? I have an application with no swap, at 16 to 64 MB ram,
running on a Compact Flash IDE card. I'm looking for good data on
whether to use ramfs ramdisk for /var and /tmp, whereas the rest of the
OS is mounted ro (to prevent file system corruptions).