It is not a ton of work, just a typical 3 to 2 rail conversion. Some of the newer cars have pads for mounting couplers, set at the correct height but many still do not.
When I first started using Kadees, I just did one car and then matched other cars to it as went along. After about a dozen or so cars, I bought a couple new ones with Kadees and realized they did not match height and would not couple. Then I learned about getting a kadee coupler gauge, or an NMRA gauge, and setting all the couplers to that height. From then on, new cars all worked with what I had - except on the very rare occurrence of someone else using a non standard height.
