I'm just a little bit worried about some situations when we want to display different information for different people. like login, membership, restricted area... With React developer tools we can change state of Components to see the reaction afer. It may be a security problem for not well structured sites

It's great! But I just wonder if I have to build more complicated app, will I need view engine to render HTML? Is React Server side rendering enough? I haven't use it server-side.