Sean, my experience with Challenge tubulars has not been nearly as negative as that of some of the other list members. While it's true that Challenges are not the quality of the Italian made Clements, precious little is these days. What they are is fairly comparable to the Thai made Clements, but as you have noted, they are much less expensive than those tires were.
I don't know if the fellows who were dissatisfied with the quality of the Challenges were expecting $100 Italian quality from $40 Asian tires, if they got a bad batch, or if the company has improved quality control recently, but I have been satisfied with them. They have been at least as round and true as any other "training" or midrange tire I have used in the past, and better than many. The only real gripe I have about them is that they are a bit dry, and would need a coat of liquid latex before use in wet conditions.
Noel Hoffmann Huntington Beach, CA.
PS. If you're really concerned about it, Sean, you live close enough to drive down here and see a pair for yourself.