FileZilla is not faster than WinSCP in general
Ha! This is so clearly wrong. There are hundreds of confirmed reports here and elsewhere. After testing on network configurations across the world I know with absolute certainty that FileZilla is way faster than WinSCP, about three times faster for plain FTP uploads. I understand you focus on other things. That's fine, but don't pretend WinSCP is as fast as FileZilla 'in general' because it plainly, provably, isn't close.
WinSCP is very good, but very slow. For now we'll have to continue using FileZilla for transferring any remotely significant amounts of data (above 20Mb or a few hundred files, say) and use WinSCP for it's scripting. It's just a shame the lead developer of FileZilla is too proud to implement auto-upload on save, and you are too proud to admit WinSCP is slow.