Timing chain tensioner

I'm certain they wear. That being said they are in a constant splash of oil and oil vapor which I'm also certain minimizes wear. I don't expect a performance engine to see more than a max of 50K miles in a specialty car. Where I am people can't easilly drive them daily all year round. If a car gets 5K a summer that's substantial. So for my customers I'd still rather have the cam and ignition timing not affected by the wear of the shoe and chain vs. the timing issues that come with just wearing the chain and having no shoe taking up the slack.
For $30, it's a no brainer for me.