The IMC rating,if taught well,is a very useful tool.for a start you are able to fly IFR in cat E or D airspace.Useful fo know how to do a LEGAL and SAFE ILS if wx gets crappy.
The chap that taught me knew I had ATPL aspirations and so we went through everything we could ,bearing in mind the course is only 15 hours,from knowing how to use the "GATE "in an NDB hold to basically conducting a safe and legal approach in less than brilliant weather when a SVFR clearance would have been dodgy due to vis etc etc.
I think if trained correctly and thoroughly it would CERTAINLY help give you a solid grounding for the IR.OH,and for the record I used mine in anger so it was DEFINATELY NOT a waste of dosh.NIMBUS is right too,it sharpens up your precision flying as well.
Cheers AUTOTHROTTLE