If the infusion is there to help you kill the Karka, i am absolutly cool with that. It would give us a sense of PvE progression within a storyline without hurting the game. However that infusion would need to be made avaiable outside of the dungeon for it to work, otherwise people that are not able to finish this instance would not be able to fight this mobs.
About the ascended gear being slightly better than the rest. Well, that just does not seem right to me. I am a hardcore player, i have the dungeon master title, and i am 100% sure i will be able to farm this gear with my group of friends. However it seems that this will toss out of the window the basis of guild wars 2 end game. It will introduce a change so big in the game that might just break everything. The gear threadmill might not be enough to retain those interested in that and will probably make those that dislike this kind of system go away.
I hope that the gear either only work in the new dungeon and have it’s stats normalized when outside of that dungeon.