I held off on the Waves v10 upgrade until today. No rush because all of my Waves v9 plugins were eligible for upgrade to v10, but I wanted to get it done before I forgot about it.
So I first upgraded Waves Central, then logged into my Waves account online and selected "get latest version" for all my current plugins.
After refreshing Waves Central, the new plugin versions appeared under "Easy Install & Activate". Selected all and let Waves Central do its thing.
All went well, but one thing I did notice after is that Waves leaves the WaveShell 9 in the VST2 & 3 folders after the upgrade, in addition to the new WaveShell 10. So depending on your DAW hosts, you may get both versions in your plugin lists after the VST scans. So I simply renamed the WaveShell v9 in all my VST paths (VST2 & VST3) because I no longer had any v9 plugins. All nice & tidy now!