Well, the WPA rules are the recognized world standardized rules. And it doesn't really matter if the players are pros or not, nor does it usually matter if the match is being refereed. You can find potential arguments in just about any rule set if you look close enough. And if there is no ref then it doesn't matter what rules you use if one player wants to argue about it.
Having said that, I do like the way the BCAPL rules are written. By and large they are the same as the WPA rules for most games (not saying there are NO differences). But I also like the that they have applied rulings to augment the rules. Keep in mind though, that the BCAPL is in a position through its league system to get instant feedback on rules issues and can more quickly update or apply a ruling as needed.
As far as an equipment violation goes though, the same thing applies in the BCAPL. If there is no ref presiding over the match then who is going to declare an equipment violation unless the opponent complains to the LO?