Here it is. The solution to PvP nerf conversations. If someone kills you with a gun you consider "OP", then switch to that gun and use it. If said person continues to kill you with "OP" gun, they are simply better than you and there is nothing you can do about it.
After that the noble thing to do is every time you see said person, immediately jump off the map if you can, if you can't jump off the map wave for respect, die and shut up.
EDIT: I wasn't expecting all these replies! Thanks everyone some great point have been made! I was kidding about the jumping off the map thing although it is always hilarious when I do it. Lots of messages about it in my inbox!
The solution for nerf posts is for people to realise that nerf posts make little to no difference. They might direct Bungie's attention to an issue, but any decision to rebalance weapons is based on analysis of gaming data and Bungie's discretion to alter their game. Let the whiners whine - they're just wasting words.