First, I definitely agree that natural selection is a huge benefit over allowing weak individuals to add their input into a captive population and as you said, Kent, chameleons have shown themselves to be able to expand into large, flourishing populations with a quite small founding population. That said, I think there are a couple different angles to this discussion about the value of FL WC animals compared to CBB animals.
The first angle is that size and color being equal, are FL WC Ch. calyptratus inherently more valuable than CBB? I would argue that they aren't. While I would agree that the resultant CBB progeny of 30 T. j. xantholophus wouldn't still be around after 35 years without natural selection, I don't think the same is true for Ch. calyptratus necessarily. If my options were getting 5+ generation CB T. j. xantholophus blood or less common US WC T. j. xantholophus blood, I'd pay more for the US WC T. j. xantholophus blood, even if the coloration wasn't as good and even if the animals were not any larger simply because of how strength decreases in each CB generation for this species. If I had the same option with Ch. calyptratus, I don't know that I would pay extra for FL WC blood where the animals were not as colorful or any larger.
The other angle, however, assumes that FL WC animals, having gone through a series of natural selection generations, tend to yield larger animals, having not had the input of weaker individuals and also having had well rounded natural nutrition. While this is often the case with FL WC animals, it assumes the specimens available are in fact of superior size and nutritional strength than the available CB animals. Not all of the FL WC animals I've seen are particularly large animals, however, and many of the large animals I've seen look like crap. Not all FL WC animals are created equal, in my opinion, and I think any higher value is due to the genetic input of a large, colorful animal, not necessarily just any FL WC animal.
Chris