Never,ever, ever, would I replace a failed IDC connector with another IDC connector. Once you start crimping on Trifurcon Molex connectors, you'll be addicted to crimping on connectors for all kinds of stuff. Buy a good set of crimpers and a stock of connectors and go at it.
However, it is good to have the wire insertion tool for when you just want to add a wire to an existing IDC connector for a mod. For example, adding a real knocker to a Stern.