Out of curiosity, what happens if you upgrade the Securitrons but then go NCR? I'm playing a character who initially will side with House but then will turn on him when he asks her to kill the Brotherhood, however by that point I will have upgraded the Securitrons. I had a quick look on the wiki, from what I can tell it seems like all the Securitron endings don't occur - presumably as there's no one to organise them - but I was interested in confirming this.