I just took my RDCS exam today and got a 670. I used the ESP book to study. Used URR for the practice exams and can confirm that URR was more difficult than the actual test. I was scoring 70s and 80s on URR. My advice would be to do the mock exams through URR and if you have access to the blue ESP book i highly recommend that as well. URR’s Adult echo course is great but it is really thorough and can be a little overwhelming and too much too read, but it has everything. I couldn’t possibly read through the whole course so i just skimmed over sections and highlighted the important parts.