Ah, I've just realized that FirmwareSender is normally used on patch binaries, not sysex files. So it can be used to just convert binary to sysex or also to send results to device. But it looks like it can't read sysex without converting it. I think we should wait what @mars has to suggest. Maybe firmware sender could be updated to read sysex files as input, which would make it useful for loading patch copies.
Another option would be an HTML/WebMIDI based patch uploader. We have something similar for firmware updates. This would be usable from a browser window without requiring internet connection.