[Brian]

Sandi, the OmniFocus application and your OmniFocus database are stored in two separate locations, and the changes we made to the App won't affect your data at all. I've actually been running both versions on my machine here for a couple of weeks.

(There was a bug that could cause OmniFocus 1.6.0 to crash after 1.7 had worked with the database; maybe that's what you encountered?)

I also synced OmniFocus 1.7 (from work) with OmniFocus 1.6.1 (at home) until today. Didn't notice any problems with my data during that period. Basically, if you reinstall the OmniFocus 1.6.1 application from our website or from Time Machine, you should be able to pick up right where you left off.

Just don't let Time Machine touch any of the files in your Documents or Library folders and you should be okay.