I am using Google Drive to save my projects. When saving it takes a little more time but I did not exprienced problems. None of my projects where ever corrupted or damaged.
However, here I have a high speed DSL connection. In Botswana I have very poor and slow internet. I will ask my wife in Botswana to open and safe a "dummy" project created from my largest project. If that is going fine, I think you will be safe. Our internet in Botswana is really poor.
When I was in Botswana back in June, I had no problems at all using Construct 3 despite the poor internet. It seems Construct 3 does not put heavy loads on the internet connection.
One of my main problem is that whatever I do, I cannot use the offline version. It simply does not reload (pressing CTRL + F5) anymore and seem to be gone after closing Construct 3. But it will be solved in the future with the standalone version which is fine for me.