, I export the edited photos from one Mac as an Aperture library (to keep all adjustments, as well as the original image format), and then import the library into the second computer. This is slow, inefficient, and needlessly cumbersome.
But that is exactly how it is done. There is no safe way to sync two Aperture libraries right now.
The only other option would be to share the Aperture library between the two macs by putting it onto an external disk and to connect this disk to the mac you are currently using, but that defeats the purpose of a laptop computer.
You could also use a backup software such as Superduper. It usually makes a backup of a complete drive, so to avoid changing the whole drive on the second computer, I would create an extra partition on each computer put the aperture library and photos on it and use the smart update feature of Super duper to back it up. Now that should work if you are the only person editing the files, and provided that you do not make edits on both systems at once that you would need to merge.