What I’m suggesting is that you draw the artwork to a BitmapData at runtime. That way file size will not be affected, and you can easily draw a very high-res bitmap (e.g. 2048x2048) so that it will remain crisp even when you zoom in a little. But you’re right, vector graphics will always have a certain crisp to them that is hard to simulate when scaling bitmaps and therefor interpolating between pixels.
It’s important to understand that Flash Player 10 (and earlier) has absolutely no support for proper 3D. The fact that Away3D manages to pull off vector-based 3D drawing is a bit of a wonder in itself, and when it’s not working ideally, that’s not because a bug but simply because it’s impossible. Pushing the limits can sometimes come off as really cool, and sometimes it can be greeted with an unimpressed “but why isn’t it working perfectly?” The reality is that it shouldn’t work at all, and knowing this, it is important to limit one’s use case to that which is possible, limits pushed or not.
So, my advice to you, if you cannot get it to work using ownCanvas, is to draw your artwork to a BitmapData at runtime using BitmapData.draw(). There simply is no other way to achieve this using the Flash platform, with Away3D or without.