A few points here:
1 the company were not SKY but were allowing people to believe they were Sky. The waranties were not useless pere se, they just weren't from Sky. the report actually said that Sky took the company to court to stop this inference.
Secondly, it should be pointed out that the insurance is for the dish as well as the box. If you pay £5 per month that's a total of £60 per year. I believe that this is the cost of one call out. My friend, who has the insurance, got a new box when his old box failed. As the box is about £100, this could be seen as value for money. As I said earlier, the HD boxes aren't that reliable (my new one broke down after only two months). So £5 per month is better than having to pay £150 for a new one.
I suppose it is a gamble, as is most insurance. The choice is yours. But as yourself, do you feel lucky..?