Capacitor is alpha and if I remember correctly the blog post “not production ready”, but I did tried so don’t know more than that.
But generally speaking, Capacitor is not a replacement for Ionic 3.
Capacitor could be seen kind of as a “replacement” for Cordova, but if you want to know my thought, it gonna takes a while or might even never be full replaced. The Cordova plugin list is just huge.