Completely agree with High Wing drifter,
The only good an IMC rating will do to your CPL test is to help you with tracking a VOR, wich is easy peasy in comparison to what is asked during the IR.
However I suspect that the IMC will give you the bad habit to scan your instrument instead of keeping a good look-out !
The examiner I got during my CPL test mentioned several times before the test that I should keep a good look out. What he/she wants to see is the safe operation of a commercial flight during VMC operations. look out = good traffic separation = safety. I insist on that as he failed 3 of my mates who didn't follow what he said or failed to understand the importance of it. With that in mind an IMC is pretty useless. And it will cost you more dosh. I didn't have my IMC prior the I/R but I still passed it ! Superfly