Strongly suggest repairing your database (=Library), making a new backup, and confirming that your Library works and that all links are in place, before moving forward.
Directions for database repair are on this Apple support page.
You should repair your Library after _every_ force-quitting of Aperture. (Databases today are self-maintaining. They _really_ don't like having the power pulled.)
Don't have any idea why the SSD to SSD xfer runs slow. I would try to let it run overnight and see if it completes. You might try a straight Finder file xfer to see what throughput you get.
Keep us posted.
You have TWO SSD's in a MBP? How?
Message was edited by: Kirby Krieger
Thank you very much for this information. I repaired my Aperture library as you suggested and was able to transfer all the files. The problem seems to be with accessing the second SSD (it was put into the CD ROM area after that was removed - this was done by an authorized Apple service center).