Hi, I understand the caption on the Ignore setting is actually a typo (or 'slip of the brain'), as it may (as per the contextual Help on that page, 'only for some FTP servers'), actually improve performance (if we would otherwise need to send separate SIZE commands - not applicable for FTP servers that support MLST/MLSD). It will have no impact on disk-to-disk transfers, as we get all the metadata in one call.
Note that it's entirely possible that some devices (think 'multi-media', e.g. cameras, musical instruments that use disk storage...) do not update LastModified (some of them don't even use it, hence it's blank), so there is certainly a case for detecting Size changes, as they may be the only change we can rely on.
You can set Pro (on the same Compare Options > File Size page) to Ignore files of less than [1] byte, but that only works if they are both zero-byte (Source and Dest), otherwise it will pick up the one that isn't. Bear in mind that zero-byte files are not uncommon, and it is possible some processes use zero-byte files to record information (by changing the LastModified stamp, to be referenced later, or even just the presence/absence of the file itself), and Ignoring these (no longer updating these by copying to backup, etc) may actually introduce errors on any Restore...
Note that it's entirely possible that some devices (think 'multi-media', e.g. cameras, musical instruments that use disk storage...) do not update LastModified (some of them don't even use it, hence it's blank), so there is certainly a case for detecting Size changes, as they may be the only change we can rely on.
You can set Pro (on the same Compare Options > File Size page) to Ignore files of less than [1] byte, but that only works if they are both zero-byte (Source and Dest), otherwise it will pick up the one that isn't. Bear in mind that zero-byte files are not uncommon, and it is possible some processes use zero-byte files to record information (by changing the LastModified stamp, to be referenced later, or even just the presence/absence of the file itself), and Ignoring these (no longer updating these by copying to backup, etc) may actually introduce errors on any Restore...