If you want your IF ability compared to that of a Private Pilot with 40 odd hours under his belt, fair enough an IMC rating would do it.
But if you want others to rely on your IF ability, why wouldn't you do an IR? There's nothing terribly difficult about it you know!
PS. It's a popularly held misconception that you need to be flying 'in cloud' to require IF skills!
In a helicopter, that frequently isn't true!
And once you are IMC, who knows where you may need to go to get out of it!
Think more carefully about it mate.
PPS. I too was a Police pilot for over 7 years.
Cheers