Well, that makes sense, you doing things completely, well, odd. Why would you not pull the drive, hook it up to a bench computer and transfer it to another drive that way? Makes no sense, especially for slower computers. In fact, Mint would not even make sense for this either. The only time I do not pull a drive and hook it up to a bench computer, is if it's an AIO Desktop or a laptop that requires to be completely taken apart to get to the hard drive, in which case, they are more likely to be faster computers.
If you are only using Live Linux CDs for this purpose, you are severely limiting all that you can and should do with Linux. I personally have several machines with Linux on them (only 2 of them have windows installed) and they all do my diagnostics, data transfers / backups, recovery / forensics, cloning, ect. The only time I use a live cd or usb is to for the computers mentioned above and to quickly eliminate issues as hardware or software related, which is much easier to do in Linux Mint.
Again, if the only reason why you are using Linux is do data transfers, then you are severely limiting what you can do as a tech. If you are still leaving the hard drive in the machine instead of pulling it out, then you are not using common sense. If you are opting to use live CDs in general instead of having a dedicated machine to do the heavy lifting, then I suggest that you change your way of thinking.