actually, i find JR Calvert's commentary usually quite good and often focused more on the game than many ramblers (not always, but often). and when Inside Pool had Dan Wallace on board for the 2012 DCC Challenge, his commentary was among the best i've heard. he's a 200 ball runner, so i believe he Does "have a clue", and he's far more erudite and amusing than other pool commentators, with the exception of George Fels, who, come to think of it, also did some commentary for Inside Pool at the 2011 World's 14.1.
in addition to the great ones you mention, i would add John DiToro and Bill "Weenie Beenie" Staton, both of whom were understated but studious commentators on 14.1. oh, and Nick Varner, of course.