The AS3 compiler in Flex is junk. My buglist over the three years I used it was nearly 100 items long. I don't know of a single unfixed issue in Haxe.
Plus, if you write the code properly, you can port it to nearly a dozen platforms (serverside, plus all of the ones on http://haxenme.org).
I don't make Flash games any more except for hobby projects, but migrating off of Flex was the best decision I ever made.
Frankly, complete rewrites under these circumstances are a cop out. It's an easy but ineffective path. What they should be doing is unit tests, isolating bugs and strictly controlling quality. Common bug reports should be triaged, rather than ignored (it's not uncommon to have a bug, and find a set of posts years old discussing workarounds). All it would take to fix Flex would be the will to do it.
The rewrite will have a whole different bunch of issues, and be similarly problematic. It's not like Flex was a bad apple in a bunch of well engineered Adobe software.
Same goes for the example apps I've seen at Corona's case studies (http://www.coronalabs.com/resources/case-studies/) and Appcelerator's Titanium showcase (http://www.appcelerator.com/thinkmobile/showcase). Admittedly most of Appcelerator's apps in the showcase are compiled for both platforms but they also have by far the smallest amount of showcase apps.
MTASC by Nicolas Cannasse, came to our rescue and it was a good one - super fast. Nicolas is also behind haXe.
Known issues: Flex compilation is not supported.
So much for multi-threaded compiling. Pfff. I guess we will just wait until the open-source people do it, sometimes next year?
> ...
> * The function does not contain any activations
Does this mean that a function can't be inlined if it calls other functions?
The IDE is what needs demolishing and rebuilding properly.