Not really. First of all, I think the CRP-5 can do a little bit more than the E6B, particularly the Mach numbers.
Secondly and more importantly, if you look at the wind correction side, the CRP-5 goes up to 1000, and I think that the E6B goes up to only 350kts. You will get questions outside the range of the E6B.
I dont have either in front of me so this is just off the top of my head.
I know that the CRP5 is ridiculously expensive and you're thinking "why do I need another flight computer that I'll never use again?" (because that's what I was thinking when I first started). But if you plan on doing your JAA exams in the UK, you really need to get a CRP-5.