From my experience you should have at least 10 times more code in unit tests than actual code if you want to do true TDD. Also, if you achieve 100% coverage as some code metric tools tells you, you've only at least covered every line with at least one unit test. This says nothing of whether or not you've actually tested every possible input, so there will still be bugs (if you find one write a unit test before you fix it).
As for the issues you mention above, I only have a few comments.
Code bases that use unit tests at least have the benefit of being written in a testable manner. And therefore can be more maintainable.
I once thought of unit tests as useless. Because it took me more time to write them than just bust out some code. Now having successfully written a template engine using TDD I'm a believer.
If you think that all you do as a dev is put your hands on the keyboard and start typing, then having to write unit tests seems like a waste of time. But what about all those hours we spend staring at a screen trying to actually write the code or worse yet trying to figure out why we wrote it that way and why the XYZ doesn't it work like I think it should?
Now come full circle with me. What if while you were thinking about what to write or how to fix it you just write some unit tests while you thought about your issue. Some great things start to happen. First you think about the problem more. Next you are forced to come up with possible inputs, go ahead write that whacky test you don't think matters. Maybe just maybe it will help later on. Lastly, but not finally, you go back to having your hands on the keyboard more but your using the unit tests to help your thought process. And what you are left with is tested code that can be more easily refactored.
Now as for those 100 unit tests you had to refactor... Why not approach the rewrite the same way as new code? You had to think about the change, why not have some unit tests to show for your thoughts?
Lastly, if the actual typing part is taking too long. You're either doing something wrong or you don't have visual studio and resharper. ;-)
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