The amount of spreader rake will affect some of the mast bend difference between fully loaded and lightly loaded. As the rig is loaded through wind pressure and righting moment (trapeze), the diamond wire(s) are in additional tension as the mast tries to bend away in the middle.

The amount of rake in the spreaders affects how much additional forward bending pressure is applied to the mast as it loads sideways from these dynamic loads. More spreader rake means that the load on the diamonds will translate more into a forward bending moment on the mast as the load increases and you will experience a greater difference in the flexing of the mast from 8 knots and sitting on the trampoline to full trapezing in 20. Less spreader rake translates into less forward bending moment on the mast yielding a smaller range in the flexing of the mast in the same situation.

Perhaps it makes sense for the dynamic mast bending characterics to be very similar between two teams of different weights. The lighter team would want more spreader rake because they dynamically load the diamonds a little less than the heavier team. To see the same dynamics, the heavier team would want less rake because their diamond wires are actually going to carry a little more load.

Lighter teams will probably want to see the mast flex through a wider range as the wind increases. Heavier teams typically want to see it flex less to accommodate the extra weight.