Like Steve I came here looking for the same fix after upgrading my rMBPro from Mountain Lion to Mavericks caused all sorts of problems. I ended up doing a Clean install of Mavericks after wiping the drive. Have spent the past few days reinstalling applications, finding licensing information, etc. And then when I started working with Aperture only to find all of my presets, watermarks, etc. not there.
So I rebooted the Clone I made before wiping and rebuilding, and found the:
~/Library/Application Support/Aperture/ directory and the
~/Library/Preferences/com.apple.Aperture.plist file.
by using Finder Menu Go > "Option Library" associated with my main User directory.
From the Clone, I just copied both the Application Support/Aperture directory, and com.apple.Aperture.plist to my Dropbox account. Restarted rebuilt OS, and copied the files from Dropbox to the appropriate places. Restarted Aperture, and the old presets, views, watermark images, etc. were all back.
This discussion helped save me from rebuilding the above.
Note, all of my Aperture databases use Referenced Files with masters on external drive. Everything synced up without having to relocate 37000+ referenced photos used by several Aperture databases.
Tom