My experience was what I think common sense dictates. Since I couldn't see a score I couldn't let that color my opinion of a given comment and had to read it. This point alone has significantly increased my engagement in the threads I care to read and made me more carefully consider the top level comments on a story. Since pg turned off comment scores I've wondered if the primary reason people have reacted negatively is due to losing a positive status indicator. This is to say the score might have nothing to do with one's own engagement with HN, but with one's concern for other user's perception of their comments.
One other change I experimented with was moving the score of stories and comments to the far right top of the story/comment so that it wasn't the first thing in my line of sight. This helped with my bias as well.
At the end of the day this all anecdotal, and your mileage may vary.