Importing graphics from Adobe Illustrator to Flash is a nightmare when it comes to precision graphics. Incredibly enough, an utterly fine graphic in Illustrator may turn up all shoddy in Flash.
To prove a point, here's a clip of the vector curve in Illustrator at 600% zoom:
After SWF export at maximum quality (10) and import to Flash, the very same curve looked like this:
The above blue curve is fine and basically identical to the one in Illustrator, but the object that should actually fit to the curve (notice the brown area) makes a truly shoddy object.
In order to get back to the original curve, quite a few curvepoints had to be removed and handles severely adjusted in Flash itself.
The rumour says that Flash CS5 will bring changes in Text Layout Engine, introduce iPhone exporter and a lot of optimisations as did the most recent AIR and Flash Player updates. Let's hope that CS5 will also improve the precision of the graphics parser. It really should.