Chronosync v carbon copy

I'm going through the "every now and then" external hard drive replacement process, I have everything backed up securely 3-2-1 so I'm not overly concerned about losing data. (its just the laborious amount of time)
I've done this a few times over the years and whatever process I use, always seem to get a small % of the file transfers with some kind of corruption,(just like pic on DAM book 2 page 249) and physically redo the corrupted files as I come across them. I've tried new cables, different drive housings ,different drives, doing low volume transfers, different ports, etc etc. I've recently got a new i7 MB pro so I'm pretty sure the hardware stuff isn't my biggest problem. sometimes If I open these dodgy files in ACR the corruption disappears and sometimes the old dcr's open fine in Kodak but no good in ACR, its even as random as maybe tomorrow the corruption isn't apparent at all.

I've just spent the weekend keeping an eye on a chronosync mirror transfer of 1.5 TB (this took a looooong time) and after some random visual inspections I've found quite a few files with corruption issues, not just one file type (I have a mix of NEFS,DCR,DNG and buckets of derivates with various files types)
this morning I've downloaded CCC (thanks RE via alex) trashed a whole section of the transfer and I'm re doing the transfer with Carbon Copy which appears to work much faster and so far appears to have minimal file errors at all ? (in the first 80gb I've seen only one a couple)

I know this is a bit of an open question/comment, but any observations or comments ??

many thanks in advance

Chris