My personal thoughts are to try and keep the league rules as similar as possible to the NAF tournament rules. Having a single set of rules for all ordo tournaments and leagues seems like the easiest thing to do for organizers and players alike.
What does that mean for claw and piling on? I stress this is my personal preference as a player is to have claw use the errata that came out. As for Piling On, I think siding with the NAF is the best. Since we do run NAF sanctioned events and I would like consistency between tournaments and leagues we run, I feel using the NAF Tournament Rules stating that piling on does not require a re-roll is best.