because of the additional weight, 48 spokes take around 10% more energy to be accellerated just as fast as a comparable 36h wheelset...
36h is also ~30% weaker.
I actually don't have the time or the inclination to calculate it so this is just idle speculation but couldn't you use a lighter 48h rim (if such a thing exists) to achieve a wheel of similar strength to the 36h, while decreasing the disparity in weight and also moving the weight towards the centre of the wheel.
Either way I personally think the affect of weight is often overstated, plus I break enough stuff to care more about strength.
36h is also ~30% weaker.
I actually don't have the time or the inclination to calculate it so this is just idle speculation but couldn't you use a lighter 48h rim (if such a thing exists) to achieve a wheel of similar strength to the 36h, while decreasing the disparity in weight and also moving the weight towards the centre of the wheel.
Either way I personally think the affect of weight is often overstated, plus I break enough stuff to care more about strength.