I took all 5 of the practice ACTs in the Red Book and I find their content to be very similar to the actual ACT I took in December. The only thing that was “different” was the double passage, but ACT provides one of those on its website. My scores on the actual ACT were equal to, if not better than, my scores on the Red Book tests.
I think the Red Book and ACT guide practice tests are fine. Why do people complain?
They are old. People complain because they are old. As you said, there are some new changes. But if you stay on top of the changes (as you did) the red book is a very valuable book. It is great resource to learn the techniques and practice timing.
The red book is the best ACT prep book by far. I used it to great success
the act red book is definitely worth it especially for the math