So long as the project is always closed, and sync is allowed to fully complete before sleep or shutdown, and then on the other machine, sync is allowed to fully download before clicking the project, you should not have any problems. Dropbox has proven to be quite stable, and the only times we’ve really seen issues with it is when the rules are not strictly followed. Any kind of automatic management of bulk files like this comes with rare risks though, so that is what your backups are for.
And I know that particular ailment quite well. Of course, I could give myself the excuse that I needed it for testing Scrivener. Right… Great little machine though, I love it; don’t regret it a bit.
I have an excuse for buying it - a cycling holiday that needs a GPS fed with each day’s route. My iPad can’t do that, and the MBP 17 is way too big.
What I don’t have is any excuse for keeping it after the holiday. The reasoning here is: buy used MBA, use for holiday, sell afterwards for the same price. My friends are placing bets on the likelihood of me selling it afterwards …