It seems to me that we'd want wide nylon straps for the hammock suspension because it stretches and conforms somewhat to the tree and allows for the angle of attack of the load, distributing weight more evenly along stretched-out and pliable surfaces. A non-flexing strap carries weight only on the outside, up-tree edge of the strap, defeating the purpose of width at the load-bearing point.
Some spring in the suspension might also be desired, which nylon provides.
Contrariwise, on a tarp ridge line the load is perpendicular to the tree and evenly distributed over the entire width of the strap; and we would not necessarily want it to stretch in that application.
So, using that rationale I ordered wide nylon straps from Hammock Bliss, 6' long, and for the tarp ridge line 1" x 4' polyester straps from: http://www.strapworks.com/Strapworks...ling_s/174.htm
, where you can build your own. Wish I had found Strapworks earlier.