We do have some bias in the matter, however, in our experience CH blood pythons do just as well as CB babies. Thousands of CH babies are imported into the United States every year. Not all of these are honestly represented as such - some are labelled as USCB, either explicitly or implicitly.
Temprament varies individually - some animals are more easily stressed than others, and reflect this stress through defensive actions.
I recommend you deal with people who honestly represent the animals they have available, regardless of their origin. At our facility we have seen a great deal of variation in temprament and ability to thrive as captive specimens, with WC animals doing extremely well and taming down, and purportedly USCB specimens acting defensive at all times, and generally failing to thrive; meanwhile, we have also seen the vice-versa occur.
If you deal only with people who honestly represent their stock, im sure you will be succesful, regardless of the origin of a particular specimen.
Cheers.
RMS