In an application scaffolding project on which I'm working, I'm trying to decide whether to use Oslo, T4 or CodeDom for generating code. Our goals are to keep dependencies to a minimum and drive code generation for a domain driven design from user stories. The first step will be to create the tests from the user stories, but we want the domain experts to be able to write their stories in a variety of different media (e.g. custom app, Word, etc.) and still generate the tests from the stories.

What I know so far:

1. CodeDom requires .NET but can only output .NET class files (e.g. .cs, .vb). Level of difficulty is fairly high.
2. T4 requires CodeDom and VS Standard+. Level of difficulty is fairly reasonable, especially with the T4 Toolbox.
3. Oslo is very new. I have no idea of the dependencies, but I imagine you must be on at least .NET 3.5. I'm also not certain as to the code generation abilities or the complexity for adding new grammars. However, domain experts could probably write user stories in Intellipad quite easily. Also not sure about ease of converting stories in Word to an MGrammar.

What are your thoughts, experiences, etc. with any of the above tools. We want to stick with Microsoft or open source tools.