The sail cloth used on the Wills Wing T2C 144 that I have
available to me: leading edge - PX15T UV White, and for the main sail including
the trailing edge (there is no separate clothe used there) - PE10 UV White.
Click on the charts below to see them at their original resolution:

Steve Pearson writes:

UVM15T is structurally equivalent to PX15T, and quite a bit stiffer than
industry standard PX10T. PX15T is too heavy to use as a main body fabric. PE10
and UVMPE10 are structurally better than UVM15T (PX15T). PE10 in the forward
body really helps keep that part of the sail clean and tight at high VG
settings. PX10T and PX05T just blow out at those loads.

The graphs show that our UVMPE10 laminate has 8% lower stretch at 100 lb. Load,
and 35% lower stretch at 200 lb. load than PX15T (which is 60% heavier). The
lighter weight allows us to use it for the whole sail body compared to just a
narrow strip on the trailing edge panel. This is important because the interior
of the sail is more highly stressed at VG tight than most of the trailing edge.