Save your money. The MCCQE1 is a totally useless exam which is no longer required by almost all Canadian programs. Of course thanks to CaRMS changing its rules every year, I just discovered about that after I paid for the exam. Now I can potentially harm the high score I got on my MCCEE.
MCCQE Part I and II are integral to Canadian residency programs. You do not necessarily need to have the MCCQE I prior to starting residency, but it is obligatory to practice medicine. All Canadian residents are required to take and pass the Part II at the beginning of second year, and you must have passed Part I prior to this.