I've haven't posted in awhile, but I've been running NE6 rooted with Towelroot for about a year now. I have the stock ROM installed with zero issues.
Recently, I've read around about Lollipop and saw there have been a few issues which need to be ironed out, although I've never installed it and can't speak from real world use.
Coming from the S4 which I used to flash ROMs like crazy, I've gotten used to the S5 with NE6 stock, and rooted to run several apps which require Root.
So at least for now, I'm sticking with NE6.