I like SourceGear. I like what I know about the company, the people, and their products - mostly the people.
SourceGear DiffMerge is helping me this morning. I created an FTP class in an SSIS Script Task from code I found online because... well, that's another post. At this point in my refactoring, I have implemented this class in a couple/three places. As the project has matured, subtle differences have emerged between the functionality in one implementation and others.
It's now time to fix that with some refactoring and consolidation. The end result will likely be an assembly in the GAC. (Again, more for another post...)
I'm using SourceGear DiffMerge to compare the text in the classes. Simple, clean, efficient, fast. DiffMerge doesn't automatically refactor for me. It just tells me what the differences are and where they lie in my code. It allows me many options for merging the files, but it doesn't force them on me when I start.
Maybe, just maybe, all I want to do is see the differences first.
Great product, and it's free.