Joanan, the issue is not technical understanding on my end. I'm the receiver, not the sender. The issue with Dropbox has been that my *senders* already have personal Dropbox accounts - not tied to my billing, and I don't want to have to own the troubleshooting responsibility of having to get every one of them setup with a separate local user account, across different OS's, technical skillsets, etc. It's not even possible on every common OS. Even if they upgrade temporarily to Dropbox Pro and I just reimburse them (which I offer to do), then the onus is on them to remember to cancel Pro. It's not elegant, which is why I'm looking for a better option. Google Drive is great when both parties are on Google, but that hasn't typically been the case.
I'm looking for a non-hacky solution where I pay, they transfer, and it just works.
BTW, BitTorrent Sync is actually quite a lovely solution based on my testing, but I'm too paranoid about the security risks to use it for sending intellectual property. Perhaps Dropbox is as risky and I'm just not aware, but I have read about security vulnerabilities in BT Sync.