I entirely agree with jennyema and Andy, you probably do not want the tenderloin if you are making the steak well done.
To me the advantage of the tenderloin is that is just that, tender. And I have never had a well done steak that was that. Think there are better tasting cuts than the tenderloin anyway. So why pay the freight of tenderloin when you are not getting the benefit?
Agree with Jennyema that pork and beef tenderloins are quite different, and I love the pork. But again we are on the pink side of pork tenderloins. (As a kid both our parents used to cremate, there really is no other work for it, pork. It was tasty but did not like the toughness. Believe you can eat it on the pink side with no ill effects when you buy if in the supermarket. And pink pork tenderloin, yumm).
Have been thinking about it, and am not totally sure pork tenderloin au poivre would be all that bad. Jennyema is always right on, but we might just give it a try. But there are so many other dishes we want to try.
Too many recipes and so little time. Drat.