I've always been distinctly unimpressed by the quality of pre-assembled trusses, and would never use them in my home... Sloppy cuts, cheap wood (either "engineered" wood or 2x4s with half missing from being cut too close to the outside of the tree - aka scraps!), insufficient attachment methods (plates with pointy triangles punched out and hammered on), and so forth. For building a shed, maybe... a house or garage, no. It could be higher quality trusses are available, but I've never seen them, and I wouldn't expect their cost to be competitive with doing it right.
--Bushytails