[gideons]

So you have a legacy system that is being used by other systems, you're the new super genius and can't understand the system, so you rewrite? Discounting the potential release iterations and bug fixes that are in the legacy system? Your "improved" version can't include that knowledge since you didn't understand the legacy system. Also discounting the company wide knowledge of the legacy system, warts and all that exists? Also having two identical systems isn't fantastic. Rewriting a system because someone can't understand it is rarely the correct solution. It most likely means the rewriter doesn't understand the problems that are being solved by the legacy system either.