Nobody canot say !!
It doesnot mean that if you hir Cohln, you will get PR. But from experiences people will inclined to what they did.
May i know under which cataogory you want to apply ?
If you are applying under skilled worker class, i dont think you need to go with any consulting firm as the whole process is outlined in www.cic.gc.ca.
So if you agree with my opinion, study the information in the above office Canadian immigration protal and decide your self whether you need anybody to represent you or not.
Wish you all the best.
Ravi
