Hi Ned -
A 127" wide image would have pixels about 9% larger than I illustrated below. You would be that much further from any issues with the holes in the fabric.
The fabric is reflective, but with a wide viewing width of 160 degrees, would be considered a "scatter" type screen like is found with unity-gain screens.
A 15 degree tilt randomizes the hole structures with regard to the fixed panel display's pixels. By effectively randomizing the interaction of the two patterns, moire can be reduced or eliminated. Realistically, it's a very uncommon effect, and only a concern for high pixel density images. As projectors' pixel fill ratios continue to increase and their structure becoming more smooth (e.g. Smoothscreen), it is less and less of an issue. Still, an easy fix.