so, don't get me wrong, I HAVE a full backup, and a CCC backup and do once a month a backup to the full backup, which includes applications, system, etc. But, for me I don't add a bunch of apps daily/weekly and don't do a bunch of system updates. So, that backup, running once a month to a TC in the house is fine.
But then, I have a little SD card which contains all my daily data, email changes, documents, desktop, everything that CAN and DOES change daily - sometimes hourly. I'd really like to get that off the SD card (and thumbdrive) backup and onto the nifty for regular hourly backup. For that, I only need the 20GB total. So, my 32GB Class 10 SD card works fine - and does my itunes backup too!