I'm doing research into software evolution and C#/.NET, specifically on identifying refactorings from changesets, so I'm looking for a suitable (XP-like) project that may serve as a test subject for extracting refactorings from version control history.

Which open source C# projects have undergone large (number of) refactorings?

Criteria A suitable project has its change history publicly available, has compilable code at most commits and at least several refactorings applied in the past. It does not have to be well-known, and the code quality or number of bugs is irrelevant. Preferably the code is in a Git or SVN repository.

The result of this research will be a tool that automatically creates informative, concise comments for a changeset. This should improve on the common development practice of just not leaving any comments at all.

EDIT: As Peter argues, ideally all commit comments would be teleological (goal-oriented). Practically, if a comment is made at all it is often descriptive, merely a summary of the changes. Sadly we're a long way from automatically inferring developer intentions!