Cool, another SL1 runner. Good luck!
I just started the DLC area today on my SL1 character. I'm pretty scared, since the DLC bosses are the ones I am least familiar with, and the toughest ones are resistant to pyro. All other areas in the main game are cleared.
O&S weren't so bad for me because pyro works well on them, and I've fought them enough to know how to dodge most of their moves.
was the boss that gave me the most trouble, because I usually just cheesed them with heavy armor. Other difficult bosses for this run were
(that aoe) and
, which surprised me because he usually doesn't give me much trouble.