Why does SD copy 3x as many gigs than "needed"
 

No doubt there is a good underlying reason, but I noted that there was about 6gigs difference between my original drive and my backup drive (both data drives) before I began my Backup - all Files with Smart update, yet SD said it copied about 18gigs before it was done. Just curious why that happens.

on a side note, Dave Nanian sent 5 emails to me, attempting to explain what my problem was when asked for help. What happened originally remains a mystery but I sent a flurry of emails to SD and I can't thank him enough for his numerous responses. Seriously impressive.

As I likely said in the emails, I really don't know what might be going on if it copied "more" than you'd expect (unless some source files had 'bad dates' that caused them to be re-copied).

Were the drives the same/right size when done?

yep...
 

I don't think I raised this issue in my email. I don't see it as a problem, but I have observed this behaviour on more than one occasion. I just checked two partitions that had difference of 370mb. When SD was done it said it copied roughly 1.5gigs. This is not uncommon, and yes, when it's all done the volume size seems correct, so I do assume it is due to underlying files, perhaps many hidden files, that have changed their dates and such. I was just curious about the behaviour, not concerned.

A size difference does not mean that other files on the drive hadn't changed... it just means that the total size is different... so, if you see a size difference of 370MB, more than that could be copied if the files were changed, but not in size.