Steve,
Thanks for the link. Just so you know, these ruling were made by Chris Jones of the PBUC. Subsequent to this particular ruling, Mike Fitzpatrick, who is the director of the PBUC, provided the contrary ruling that a B/R may overrun on a ball 4 passed ball or wild pitch. You can read about this in the BRD (article 109 in the 2004 edition.)
I don't have a copy of the JEA, but if it actually said that the B/R may not overrun on ball 4, I expect that Papa C would have included it in the BRD. According to Rich Ives, in a thread here from last July 27, the MLBUM also allows an overrun. And J/R allows the overrun.
So I'm inclined to believe that there is pretty good agreement among the various authorities regarding OBR-- except Chris Jones.
Of course, not all rule codes are the same: FED doesn't allow overruns, and NCAA explicity allows them by rule.
Dave