Yup, absolutely. My take is that because you get to do something fun (start from scratch in a good language), the thousands of test cases you have to write and

Yup, absolutely. My take is that because you get to do something fun (start from scratch in a good language), the thousands of test cases you have to write and then run against the old implementation doesn't feel so bad. (I have to imagine a good amount of mailing list archeology will also be required. "How did Linux mess this up in 1992?" etc.)