Hadn't used them so I can't comment. But the IM questions on the exam are seriously not hard. The best prep is just regular QBank Qs and having prepped well for Step 1. You're probably better off just spending more time on UW.
Stick with UW. We have do MSKAP questions in residency and most of the questions are directed toward readings...some of the stuff can be picky. UW is the best for CK.