Yea its a balance between risk v reward, I think indie’s/hobbyists/small studios would be ok with taking that sort of vendor lock-in/dependency for the reward of mindlessly easy distributions. But its not like setting up an FTP is so difficult either.
Feel free to run with any of these ideas and let me know if you decide to pursue the Dropbox approach. The folder-per-version I see being helpful once your game is live but right now while I’m doing small tests I’d probably just delete older versions and replace with new so your current approach is probably fine.
Let me get this up and running and then I’ll see how I fair.