Allow me to answer this by saying that you can easily get 7+ on all bands on IELTS when compared to CELPIP , simply beacuse IELTS are far more direct in it's format. However ,and this is a BIG however , writing is always going to be a hurdle since you need to write two essays (one short and one long) using a pencil, that is where people start to lose marks for handwriting style, count of words , mistakes ..etc.Btw how do you campare celpip to ielts?
If you can do handwriting very well ,and are confident that you can write a good piece and get the 7 on writing , then by all means go for IELTS , otherwise jump into CELPIP and start preparing.
So far I have been preparing for CELPIP these past few days and let me tell you it's not quite as easy as IELTS ( Reading and Listening), you can easily go below CLB9 if you didnt pick your choices right , which might seem simple enough at first but they are very closely placed and not having a good ear or eye can cost you another exam session.
So far my results using their online practice tests are variable ,sometimes I score 7 , 8 or 9 on R and L , Am not sure if this is a good indication of any sort or Am about to get disappointed at the real exam.
That's my two cents.