IO540, you could have used a Jepp CR from the start if you wished. I've been using a Jepp CR5 (the smallest & therefore least accurate of the CR series - but still at least as accurate as the UK CRP series) since 1987 when I did my Oz IR. Used it for my Oz ATPLs, FAA ATP & UK ATPLs. Some problems** require fewer steps than the CRP so that's a beneficial point to them. I also find the wind side easier no matter what type of wind problem it is. About the only time I've used a slide type since the '80's was when a student wanted to learn use one.
**Those were ATPL Mach No. problems. Don't know if the JAA IR exam goes that far.