I completed my test yesterday and am extremely happy with my results. I got a 6 on the Integrated Reasoning, which was better than any of my practice test scores. My Quantitative was a 49 and my Verbal was a 34, for a total of 690, which tied my best practice score. The dry-erase sheets were actually easy to get used to. The pens dry very quickly (within a second or so), so I never had any problems smudging the text.
I saw one data sufficiency problem during the test that was especially hard and reminded me of a practice problem you pointed out as one of the hardest. It involved finding the remainder of a variable when it is divided by 5 and the clues didn’t involve any concrete numbers, just more variables.
Thank you for all of your help with the ACT test preparation. My dad and I are thrilled with how everything turned out.