SM,
It is your pool and you should get what you want, but why go with old school DE?
I have the CCP-520, which is a Quad cartridge filter system. I love it. I will never go back to DE.
I originally wanted a DE filter but most of the cities in the DFW area require that DE filters be plumbed into your sewer, which I could not do. Now that I've used a large cartridge filter, I'm glad I did not go with DE.
I could go a whole year between cleanings, but normally clean my filter once in the spring and then once in the fall.
To directly answer your question... A Quad DE 60, 80 or 100 would all work for your pool. The bigger the filter, the less often you have clean it.
Thanks,
Jim R.