I don't think they are snake oil. Right now I don't use any but I can tell you I HATE the file copy built into windows.
The file copy,delete, move and all that in Windows is horribly slow with the larger number of files you do at once. Windows is going through all the files and getting data on each and every single file which slows it down to a crawl with large numbers of files.
A lot of times I will not use it and use the xcopy in a cmd window to copy large number of files and use the del command to delete a lot of files. They don't sit there and try to get info on the files, they just do their job and they are done.
If your going to use a file copy program make sure to research it and find reviews. Some will no doubt suck, while others will do well. In the process of making my new registry backup tool I am using an API file copy command in windows. And I have found that there is a way to buffer file copies making them even faster. So when looking for a program look at how they do
Shane