I agree with @billstevenson that you should hear a significant improvement in sound quality. If you plan on keeping the CJ amps for a long time, I think the upgrade will be a good investment. However, the teflon caps will change the tonal balance from what you are used to hearing. The teflon caps will probably result in a cooler sound with less mid bass warmth and richness, albeit with more detail.
The coupling caps in the amp now are likely film caps that should last a long time so I wouldn’t be concerned about the coupling caps from reliability standpoint. But the power supply electrolytic caps should be replaced if you still have the originals in the amps. The electrolytics do have a limited lifetime, and a failure can damage your power transformer.