le HM est individuel pour chaque boss donc je pense que ça ne change rien, vu que tu as le choix de le faire soit en HM soit en normal (maintenant je peux me tromper), l'ID comptabilise juste les boss morts quelque soit la façon dont on les tue il me semble

But let's say you are a member of a Heroic raid in Icecrown Citadel, and after killing Lord Marrowgar on Heroic you have Internet connection issues that prevent you from raiding for two nights. During those two nights, the rest of the raid kills everything. Without the Flexible Raid Lock system, you would be done with raiding Icecrown Citadel for the week. Ouch. With the Flexible Raid Lock system, you can join someone else's raid as long as they are doing Normal difficulty. This would at least give you the opportunity to earn your Justice Points for the week. If this raid attempted to switch to Heroic difficulty for Icecrown Gunship Battle with you in the raid, the raid leader would receive an error message stating that she cannot change to Heroic, because someone in the raid (i.e., you) is already locked to a different Heroic instance.

ce que tu as link Lolo était sans doute valable du temps d'ICC mais ça n'est plus le cas

L'id ne prend pas en compte le fait qu'un boss fu tué en hm ou pas . Tu peux faire un boss en hm avec un grp PU puis continuer le lendemain avec un autre grp en normal ou en HM .