I agree you need a source of regulation for the CHE, but I wouldn't say I agree with the part about a UTH being necessary.
Case in point: I don't use belly heat AT ALL, but rather only radiant heat panels for all of my animals without problems. This was the suggestion of numerous other experienced keepers as well as Bob from Pro Products. It makes sense as well, snakes don't have a source of "belly heat" in the wild to digest meals. Rather, they use a source of basking heat (which can be provided in captivity by CHE's or RHP's). Just make sure you're keeping proper temperatures directly under the bulb at substrate level.
Do the CHE's provide ample heat like a radiant heat panel? If so I totally agree with you. I believe they don't though. People often use CHE's and a UTH. I apologize if I'm wrong but I didn't realize she had a radiant heat panel.