We will be releasing a cloud sync patch this week which will enable sync between Steam installs. This is a very unlikely scenario but we must mention it.. if you load a game for the first time on a new machine after cloud is enabled and have NOT played and closed your game at least once on your main computer it will cloud sync that new save game as your primary save.
As you can imagine this would make you cry when you get home and ignore the warning that you are launching with an older file and then overwrite all your save progress.
Just a heads up to be mindful of any pop-up messages and to load and close the game so that it cloud saves your main PC.
This is currently only for Windows but we will enable OSX very soon as well (possibly at the same time if we get the OSX paths in before we go live with it).
Thanks :)