Julian
Believe me - if the 15 hours of IMC instruction is good enough, and you stay current, then it is more than an 'emergency' rating. Bear in mind that the main reason most get it is to fly on top. Then you rarely spend more than 10 minutes in the climb and descent actual IMC before before breaking out into gorgeous VMC.
Having said that - I've used it in anger when I've had to, even flying approaches to IMC minimums - if you stay current it's a lifesaver, and anything that improves your chances of survival if you end up in a bad situation cannot be a bad thing.
CM