This is a Super.
I came to Radiantubes after decades of using Calrod units. I really had no trouble. I knew that I had to watch them while on HIGH and switch the heat as soon as it was needed. I really had no problems and liked the freedom from fiddling that came with the 5 fixed heats since I had learned on 5 heat Calrods. I did a tremendous amount of cooking on my RT70, the TOL 40" for 1954. The most I did with my infinite heat units on the RCI-75-61 was make candy and do a little canning on the Heat Minder and that went very well.
It's funny how responsiveness can be a desirable quality, but if you know what you are doing with Radiantubes and don't let them stay on high too long, they are perfectly satisfactory for cooking. You just have to pay attention to what you are doing.