Even for smaller projects it may not be the right choice. I had a side project I work one that would take a complete re-write to make it testable as well as be

Even for smaller projects it may not be the right choice. I had a side project I work one that would take a complete re-write to make it testable as well as being able to work better in Windows 8. But I find that when I think about it, it's a huge amount of work and while new features and bugs can be annoying to fix (lack of tests also means inevitable regressions), but still far less time consuming than a re-write. Plus, if I completely rewrite it so it's awesome and more flexible, I expect that my revenue will probably be about the same as it is now. Rewriting it won't increase my sales unless I'm able to add features that would be impossible in the current code.