Of course it would be a lot easier to stay with Photoshop. But vectorized outlines have a very unique look that can't be accomplished in Photoshop, or at least it's a lot harder. Maybe I'll stick to Flash for outlining things and export the image in Photoshop to colour it.
I've watched a lot tutorials in the last days and it seems that Flash really got everything I need. Even colouring seems quite comfortable.

Our team is specialized in console and mobile games (e.g. iphone = no flash), so images have to be rasterized. A pity that flash is only supported on the PC.
But developing for the pc market is, in my opinion, not the best way to earn money any more. At least not for indie developers. There are thousands of free flash games, its hard to market a game with costs there.