I've seen this kind of questions numerous times and the answer is not that simple. From a technological point or view we want the latest,the hottest bleeding edge technology, because the
old stuffis already boring and the new stuff has those very nice new features which you love to use. However from an economical point of view it's better to stick to exsiting knwoledge and experience, because you're basically taking a risk with the new stuff.
Although Seam 3 has my full aatention, I am not yet using it for production environments. We use Seam 2 because of its stability and rich set of thoroughly tested features. We are - luckily - in a small markt sector with low demands so for us there is no need to use the latest stuff available.
So in short, see what the market and your company needs and adapt your technological choice to it and NOT the other way around.
Seam is a bijection framework. Why do you still need a IoC framework? May I know what kind of use cases require another IoC framework like spring or guice?