I found this comparison dyno pretty interesting. It compares the E39 and E60 M5s. Note how absolutely smooth the power delivery is in the E39. Note how much more high strung the E60 motor is - much more like the old S14/M88/S38 motors. Also amazing is how the E60 is a weaker motor until after 5250 rpm or so - despite having an extra liter of displacement and the better part of a decade of technology.