Raiding is about beating the boss and other guilds to the kills, gear is just another tool to help us get there. So unless there is an achieve or some official way to keep track of what bosses where killed with or without the buff we only gimp ourselves by turning off the nerf.
As for why/how soon the nerfs were implemented. My guild is just like several others that have already commented in this thread. The holidays kicked our asses as far as progression goes, as well as *%$#^&)(*%$ healers. We finally got settled in with our new healer last week and got H ultra and H skittles (H Yor) on in our first 2 raid days this week as well as clearing the rest on normal. Yes the kills were post nerf but they would've been killed with or without the buff whether it be this week or next. I just wonder if blizz took the holidays into account when accessing the numbers because I believe that could've changed a whole lot of things.