During a recent dungeon, my character received wounds that were filled with a magical metal. The GM ruled that these wounds gave my character +1 AC and -9 Max HP until cured. My question is: should I bother to cure this status effect? Some related follow-up questions might be: what is the break-even point for -MaxHP/+AC? Is there a general-case way of thinking about this sort of status effect?
Character-specific details: the wounded character is a level 7 battlemaster fighter who wears platemail but no shield. The character has 14 CON and (unmodified) 66 Max HP. In other words, before the wound the character had 18AC/66HP; after, the character has 19AC/57HP. I'll gladly edit with any additional requested details.
Additionally, I know there are plot considerations and so on when something like this happens; for scope's sake, this question is strictly interested in the number-craft.