Your principles thought sounds to me correct.
The strongly-typed languages like C# are good candidates for a code base that constantly needs re-factoring. Basically most re-factoring tools (like Resharper, JustCode, etc..) in the market are usefulvery effective in statically typed programming languages.
What does real world projects tell about usage of dynamically typed languages for agile methodology?
For development team that practices Agile/Scrum methodology it is very helpful (even critical) to have good set of re-factoring tools under armor. Otherwise, all sudden changes in upcoming sprint may be a nightmare to be modify or re-design.
Thus, agile methodology does not provide advantages to statically typed languages or dynamic once. What it provide is an iterative approach to build a solid application.