Build updates with open source tools?

I see that there are open source tools now available which would allow building the app.  For example [Flashdevelop](https://www.flashdevelop.org/) and [Apache Royale/Flex](https://royale.apache.org/) along with a [Free version of AIR](https://airsdk.harman.com/) including Air Native Extensions.  

Anyone with more experience migrating from the discontinued Adobe tools have any input?  

