Old Old thread. I know. I'm just trying to save my data from an ailing SSD, copying it to the NAS, and I saw the option in the dialog, googled it and reached here.
Good thing, thought. Now , to avoid the cache issue, I'll restart both computer and NAS before I use Synchronize Dirs to verify the copy
It's really out of curiosity: As the CRC is calculated on the source computer this means that the copied info has to be read from the destination compute and sent back to the source computer for CRC calculation. So, a CRC comparison should be SLOWER than a bit-by-bit one! Assume there is an error on the first bit. As it's detected immediately, the "mismatch error" could be given immediately, not after the whole data is re-read and sent back over the network...