I think part of the problem is the 2 releases this year around, don't think could have the 810 chip in both models and needed the new 6 model to be seen as a upgrade to the 5.
I'm still rocking my old N5 and it's still going great guns. Did a complete factory reset on it early in the year and it's been the best thing to happen to it, nice and nippy and the battery still lasts a decent length of time.
However i'm just using it as a bluetooth hotspot for my little laptop to use and have another phone for general use.