This is also a big issue for me; in fact, I only ended up browsing the forums because the Omni support folks just told me that I'm not allowed to leave the app running on two machines and I was pretty startled by that.

I appreciate that changing software isn't easy or quick, but I do think that until it's changed you should be making that limitation *much* more clear. I read the license pretty carefully and did *not* come away with the impression that I was violating the license terms, and the 'Not licensed' error message certainly didn't help explain the situation.

The iPhone syncing is great, but as far as syncing between two machines goes, if I have to remember to quit one copy before opening the other, I'm afraid I don't see the point of having syncing at all — I might as well just point the database at a shared filesystem or stick it on a USB drive and carry it around with me.