The most important hunk of meat for me is the beef tenderloin/filet mignon. I enjoy it for it's tenderness and lack of connective tissues. There are other cuts of meat that are more flavorful, as you are dealing with fat and connective tissues, which add much to the flavoring.
But I don't see any differences in a prime cut of beef tenderloin vs. a choice cut. How would they be graded? By the fat content. And the beef tenderloin cut is a hunk of seldom used muscle. without a significance amount of fat.
Perhaps someone could further explain the grading steps involved in the process of Choice vs. Prime, but I say there wont be any significance in tenderness and flavor once it's on the platter.
I think you are correct.
Unfortunately, when the beef grader grades a side of beef hanging in the cooler, it's done by examining only the prime rib marbling. They always cut between the same two ribs, I think 7 and 8, and the grade covers the entirety of both carcass halves. How this grading carries over to cuts without intramuscular fat, like the tenderloin, will fuel a three-hour discussion.
Butchers and slaughterhouses have long recognized that grade-labeling organ meat and other portions (tails, shanks, neckbones, flank steak...) don't provide a profit increase. However, the average consumer would assign a premium to a prime tenderloin over a choice or select. So, if the consumer is happy to pay more for a prime tenderloin, the retailer is happy to collect it.