Sync Toy vs XXCopy

Learned about Sync toy in this forum. How does Sync toy compare to XXCopy?
http://www.xxcopy.com/index.htm
Installed it today, v2.0 beta.

That is, will Sync toy when doing a second or third back up simply by pass
unchanged files, thus saving time?

It seems that it will pass them up and I am excited about using it but I
wish to get to know a bit more.

Sync toy may even be a better solution for file and folder back up than
xxcopy?
Thoughts.

Trial and error, I suppose.

Robert