Thanks for the link.
Not portable... And doesn't seem like it can do partial file updating, copy open files or detect renamed/moved files/folders though.
True, Bvckup is the more advanced tool in the respects you mention. Also, CopyTo has no realtime sync. No doubt, I remain very impressed with Bvckup's capabilities.
On the other hand, CopyTo Synchronizer can perform differential backup, incremental backup, and bidirectional synchronization.
I suppose it's a case of the right tool for the right job.
[edit: excepting renamed/moved files from the first sentence btw.
I realize Bvckup doesn't do that yet