I've used the CR type (a CR5, specifically) for all my ATPLs, incl. the UK one. I find it easier & quicker to use than a slide type - especially for some problems. It's also pocket sized.
The argument concerning 'CRP5 is the one the examiners use' is irrelevent. In the class with ~ half doz. CR users using the smallest or second smallest type (and therefore least accurate) we all consistantly got a smaller spread of answers between us than the CRP5 users. Our answers always agreed with the median answers from the CRP5 users.
The catch with using one in the UK is of course the lack of instructor knowledge about them although the instruction book is easy enough to follow.
Curious that the UK never embraced or has hardly even heard of them...
