Currently we are on version 8.0.0.917 and from the server, I get this pop up to saying its a mandatory patch (remember seeing it).
I don't see version 9 under our customer download page. Should I go with the update 3 for now if it is a must? We don't have any issue with our current version.
Upgrade to v9 from v8 is supported from any patch level - so feel free to upgrade at your own convenience. If you would like to stay on v8, then installing latest update is a good idea. It's always good to have your installation up to date to avoid known issues.