I was wondering what effect difficulty had in world tour. At first glance, it may seem that it is easier to play at easier difficulties in order to make it easier to get more stars and thus progress faster to other cities, but I suspect that there is more money and more fans to be gained by playing at higher difficulties.
If difficulty does affect world tour in some way, I have an added question. When a band is playing, is there a point of playing at expert vocals for instance as long as somebody else is playing at a lower difficulty?