Ric Hjertberg, founder of Wheelsmith, thinks people should use spokes with thicker elbows in a lot of rear wheel builds. Because spokes that break almost always break at the elbows, and thicker elbows (2.3/1.8/2.0 for DT Alpine III, 2.2/1.8/2.0 for Sapim Force) add a tiny bit of weight to have about 1.25 times the cross-sectional area at the elbow and thus significantly less likely to break there. For a touring wheel that will see heavy loads, with only 36 spokes, this is probably a good way to go. He thinks this matters significantly more than thinner NDS spokes, and says the value of butted spokes is still largely a theoretical proposition that is nearly impossible to prove empirically. (He engages this more in the comments section of the link above)

I've been very interested in figuring out optimal design for a dished rear wheel, and like the idea of asymmetric rear rims and/or thinner NDS spokes. My sense is that, empirically, it's difficult to show that either of these has the benefits. The most important thing is to build the wheel well, with consistent tension on each side, and tension not too high for the rim.