I’ve been using Plex Cloud and Google Drive for more than 2-3 months now, I was one of the first users get the invite, so far it’s very good and it’s fast.
At the beginning it had lots of bugs but now it’s very stable, I know sometimes it take time to start the server or sometimes it take forever to get the media content after library scan, but it will do the job.
I have more than 65Tb right now on Google and so far everything is smooth and I never get any ban so far, thank god
P.S. I even had 6 streaming with it, but right now I read in FAQ that you can only have 3 transcode stream on it, so you have to consider that too when you using it.