I've used both but I'm not part of the Appcelerator cult like most people who have invested in it apparently. Appcelerator is bad. Their OSS license is sketchy last I checked. But that's not its only problem. The community is driven by a module marketplace, which means a ton of okay-quality modules now cost $5 each. Not necessarily a bad thing, but React Native developers are releasing way more modules as FOSS, which is important to keep the community growing and active. Another thing that doesn't generally seem possible in my time with Appcelerator is being able to build a view hierarchy using native UI components. That is, I can't for example create a camera viewfinder as a background element and throw my UI inside of that element.
React Native in comparison has taken the path that is best for FOSS developers at every step of the way, which makes me very happy about the future of the platform.
Actually no, POCs have been made which allow you to deploy setups which allow for live updating apps in production. Apple even allows RCE as long as it's executed in the JS engine.