After completing the old UK ATPL's in June, I would say the CRP5 is a 'must'.
Assuming the JAR exams put you under similar time pressures,particularly Nav, you will find that accuracy is easily lost on the smaller,more crapmed scale of the '1.Plus,if you do some brush up work with Baz at Bristol,(recommended),he will show you some of the cracking short cuts on it, and you should finish up with the correct answer every time!
Good luck with the exams and good choice with Bristol !