I originally bought Intego Personal Backup x4 which I found to be a solid program and then later updated to x5 about 3 months after x5 came out because I wanted the synchronisation functions.
I CANNOT recommend Personal Backup x5's synchronisation function. It is a horridly bug ridden program for synchronisation (which is a new feature of x5). For that, you should turn to ChronoSync.
Intego's technical support is also very horrible in responding to customer technical problems. They do not respond on time, if ever.
I was having a lot of errors when Personal Backup x5 was performing a synchronisation between two folders that exist on two different computers. The folders are 5GB in size and usually took over 45 minutes for the synchronisation to complete (and with errors) each time, not just the first sycn.
I finally gave up x5 hoping Intego would come out with a fix. They have not been responding to my requests for help nor have they been acknowledging that their program has bugs in it, if that is the case.
I've turned to the demo version of ChronoSync and the makes of ChronoSync have give me a time limited, unlimited data transfer serial number for the mean time to fully test out their program before I buy it. Using ChronoSync to perform the same function of syncrhonising the 5GB folders, the sync happens very quickly (in a matter of less than 4 minutes) and with no errors.
ChronoSync has not given me any errors. Intego's Backup constantly gives me errors and Intego's tech support seems to be indicating that it might be something I'm doing wrong. That is likely not the case since I have no problems with ChronoSync.
If you're considering a sycn or backup program, I recommend going to ChronoSync. It doesn't only do syncs, but backups too. ChronoSync will soon have the ability to create bootable backups too. Besides, ChronoSync is a cheaper software at $30.