Veeam's product has evolved into one of the fastest secure copy software available out there and it's free! This is not a paid advert; I am an active user of WinSCP but lately I decided to try out the latest version of FastSCP and was surprised with the speed and additional features it has. I used previous versions of FastSCP and was convinced to switch to something else but now, I decided to go back to Veeam's free product.
FastSCP uses the full network capacity which makes it very fast but one needs to be cautious when triggering large data transfers as these may saturate the network. I suggest that you should assess your network environment and find the best times to perform bulk copies. In fact, some products do specifically have limitations on bandwidth usage. On the other hand, FastSCP has additional features that improve file copy performance and can provide secure connections. Frequent users of such utilities know that security is achieved through SSH as is the case with this product, but FastSCP does not require any modifications on the server side (ESX & ESXi). The file management supports drag and drop functionality similar to windows explorer and can send you an email to notify you that a file copy was completed.
To download a free copy you need to register using your email address. Go here to register and download a copy.