Hi tingtang, you seem to have reasonable experience already on M/E piston A/C. When I did my CPL I figured that a multi CPL was the way to go, to help gain extra experience for the I/R later.This probably ended up costing me extra money than I had planned for because for your CPL flight test you need reasonable flying conditions (vis etc) and I didn't get suitable flying conditions around the time I was ready for test (extra hours in twin =££££)
having said that , it did make the I/R easier, so money well spent in my case
cheers M