I can think of loads of people who are two for three (Eekhout, Prineas, Rosenbaum, Cat Rambo to start down the path inexhaustively), but I can't think of anyone else who is three for three. Mur has been on all Escape Artists casts as a reader. And if Steve ever read for PP (I can't recall just now if he has, and of course I don't listen anymore so I may have missed it), he's read on all three casts.
Good question, Ocicat.