Never mentioned so far, but:
rsync does checksum src and dst files in multiple chunks to verify if they are different. It's kind of a speeded up, distributed binary comparison. This is by far a more reliable procedure than comparing modification dates and size etc. of the files which is - at least for me - too error-prone.
Thus, GREAT that you have rsync feature on the todo list - nothing else expected from the builders of such a great tool :wink:
I vote for this too. I discovered that synchronization with WinSCP (timestamp and size) wasn't working sometimes because I did a "synchronize timestamps" and then a diff between two directories and I had 2 files which has the same size but not the same inside and then WinSCP concluded that files were identical (same timestamp and same size).