Cathy Duffy has a review of the new one.
I prefer the older version mostly because I don’t need the reading, vocabulary or spelling parts. We use other curriculum for that.
Also, in general when Masterbooks changes old curriculum they switch to their style which is more worksheets. It can be tweaked, but we went with the older one.
Cathy Duffy said the older one wasn’t organized well and was difficult to use. I didn’t like or use levels 1 and 2, but 3 on up worked well for my son.
As far as being CM, I don’t start formal composition curriculum until junior high, and I don’t worry much if it’s CM because we don’t do composition curriculum constantly throughout junior high(middle school) and highschool. We do just enough for my teens to feel comfortable with formal writing, which varies for each.
I used some IEW with some of them too.
My current 6th grader is using an out of print curriculum called Understanding Writing, and my teen uses Writing Strands.