A problem that I see with Mikrotik, and the way most people (myself included) roll it out is this, if I understand things properly:
DNS Cache and Proxy cache is both written to the drive (volume)
The drive is gennerally a compact flash card, which has a limited number of rewrites, and then needs to be replaced.
My Idea is this: If there was an option to create a RAMDISK and mount it to put proxy cache and DNS cache on, then fewer writes will be needed for the compact flash. Both of those types of data can be rebuilt with minimal impact in the event of reboot.