[whpalmer4]

Let's run the numbers, shall we? OmniFocus will do a backup once or twice a day, plus each time you quit, if you so choose. Typical database size is well under 5 MB, but we'll call it 5 MB. We'll be conservative and say 5 backups per day, plus an additional 5 copies in Time Machine. 50 MB/day is not exactly a footprint that is going to run someone out of disk in a hurry. I haven't discarded any backups since the beginning of May, and have only lightly pruned the older history stretching back nearly a year. The backup folder occupies 3.4 GB. I just bought a disk yesterday. A 2 TB disk in an OWC Mercury Elite-AL Pro enclosure with FW 400/800, USB 2.0, and eSATA interfaces works out to be about 42 cents for that 3.4 GB. Raw disk cost is about 40% of that. So, once a quarter, I could spend about 30 seconds to delete the previous quarter's backups, and recoup 42 cents worth of disk space. OmniFocus could easily remind me to do it, too :-)

For most people, it isn't a problem. For the remainder, the Finder works well (and is available at no extra cost), or something like Hazel can be bought and put to multiple uses besides pruning backups. Omni isn't likely to spend the effort to do anything fancy if there are few requests for the feature, so anyone who is particular about what gets kept probably still will want to roll their own solution.

We were pretty excited at our good fortune when the Unix systems I managed 20-25 years ago had considerably less than 3.4 GB of total disk space to serve 30 or 40 users!