I have the remnants armor from the auld an syne quest and I have christine's combat/sneak armor, whatever it is called.

I read that a lot of the baddies in LR will use weapons that do extra damage to power armor, like maybe arc welders? and that tunnelers and deathclaws ignore armor.

so what armor are you using, and how is it going?

I have found a few of the fights deadly in that I died the first time but kicked butt the second

I went in with the vault suit and then bought the riot armor from the commisary. I then upgraded the advanced riot armor and then Elite and it's been going fine.

I went in with gecko backed reinforced leather ditched that for some marked man armor and then the riot gear and its upgrades, I'd go light or medium heavy would be useful against the marked men since only 1 had the arc welder but about half the time your fighting tunnelers or deathclaws which ignore DT so I think PA isn't very useful for the sligtly higher DT you'd have.