A few things to keep in mind:
1) There is no way to reliably mark which guilds did EC NiM on the PTS. As mentioned, you could have guilds that went in with a few members and PuGed some of the spots. No one has tracked this or could successfully track this.
2) Unless you record and post your entire raid and someone watches it, there is no way to prove you didn't skip bosses on NiM by doing them on HM, jumping out of the instance and switching to NiM.
3) Aside from some people in the few remaining 16-Ops guilds in the game, no one really cares about these rankings of guilds or who killed a boss first. At best it should be a friendly competition between the few 16-Ops guilds left in the game because no one gains anything from beating another guild to a kill... aside from bragging rights that no one outside of these guilds cares about.
That being said, I think it's cool to keep track of what guilds are still around and clearing stuff on 16 so I would put my vote behind someone creating a simplified, non-points version like I did for 16-TFB HM. If someone does that and keeps it updated I will gladly post our guild's kills in that thread.