Are you saying that if C1 V7 crashes whatever work you did before save is actually lost? That would stink!
The reasons for going catalog are simply that for the moment, I can not use Lightroom for .MOS files. I could run them through the Leaf RAW converter, however then I would lose the ability to apply a LCC after the fact and I sometimes play with the LCC to lower contrast in images in C1 so it would be silly to convert the files (which are larger in MB's) just to use LR. I don't like the idea of having two catalog programs, but I'd rather have my MOS files organized so that I can find things which is harder now. Still my preference would be for Leaf/Apple/adobe to work together more such that the compressed MOS files could be opened and managed so that I could continue to use sessions. The idea of a session - shooting in the studio on the laptop and having an easily boxed up and migrated package of files makes a lot of sense. PhaseOne would do well by making their catalog function better integrated with the sessions so that it isn't so much an either or situation. I wonder if they couldn't do the catalog database but still keep the previews, keyword and adjustment data in the same format and location as the sessions do?