So while I see the logic behind making companions unkillable (you're going to just reload the save if the companion dies because you don't want to lose them), I feel like it kind of breaks both immersion and difficulty a bit too much. One of my biggest complaints with NV was making companions immortal; it feels unfair to have an unkillable bullet sponge that can also dish out significant damage; its a perfectly viable strategy for me to just hide in a corner while Veronica runs around in power armor beating the crap out of everyone with a ballistic fist- if she goes down, all I have to do is mop up the one or two people she couldn't get, and bam- nothing lost.
Now I understand I could enforce a 'reload last save' policy on myself if my companion goes down, but it would be much nicer if there was an in-game option to automatically kick you back to last save-point if your companion goes down. I doubt Beth will give us this much option customization, but hopefully there will be a mod down the road for it (God I'm so excited that the Xbox is getting mods).