Higher revs help smoother gear changes, especially when the engine is either cold or hot.
30mph in 2nd gear is under 4k revs so, IMHO, there is not much need for a higher gear and you get a bit of engine braking or throttle response if needed.
Also, on my old Diversion (air cooled but I guess the principle is the same) using a 'cheeper' oil such as Holfords own did not help with gear changes when the engine was hot, but switiching to Castrol GPS cured it (well, helped a lot anyway).