At this point armor is in short supply. I do have some NCR armor that I know Boone will wear.
Question is will this provoke even more factions then just the Legion (they hate me and Boone anyway).
BTW Boone seems quite eager to skip his beret for any helmet, I prefer he has it on if only for the crit bonus.
Does he benefit from the crit bonus?

Faction disguise effects don't appear to apply to companions. Nobody ever cared about Veronica wearing Brotherhood Power Armor for me.

Going into Red Rock Canyon with Boone in his 1st Recon armor made them hostile towards him. I was accepted by them. Fast Traveled there and walked into Papa Khan's house and it was an instant battle. I reloaded and went back there with him in the Bounty Hunter Duster and they didn't attack him.

I love that duster. Boone can have all the armor and PA I have but he's not getting my Bounty Hunter duster.

And I leave Boone far away from the Khans. They like me so I'm not worried while I'm there.

Boone with just the 1st Recon beret can anger the Khans, but I wouldn't be surprised if it pisses the Great Khans off if he wore the full uniform.

Same experience here. I also had Boone wearing ranger combat armour for a while and nobody objected.

Boone could be wearing underware and him and the Legion hate each other....well Boone hate's them more, he just own's his Legion hate so well.


bigcrazewolf

I've never had an issue w/Boone and the Khan wearing non-faction armor. I don't like NCR armor looks so I never let him wear it. So all I can say...try it, if it triggers something reload and just take it off.
And yes I believe his beret does affect him, like most things can. Oddly, he refused to wear many hats for me for a long time, as long as his beret was in his inventory, but he did like the space helmet. Now he seems to be more willing to wear hats...either my 1st game was glitched or something changed in the patches. Knowing this game, I'd guess the former...