All the previous true, another great factor is there's some 7kts difference in Vref 30 and 40 and at high gross weights that extra speed at touchdown equates to a noticeable (and at times scary) amount of extra runway especially when compared to the classic.
The other time it should/must be used without question (unless you have an obscene amount of runway available) is when you have any tailwind component.
I know of a few guys who have gone about as far as you can go, without becoming a statistic and from which others can (hopefully) learn, by using F30 when operational considerations should have mandated F40.