I have a ton of merchantmen and bulk freighters I made the first couple of turns and sent out, I have not seen anything cool happen with them yet. They took like 4 days getting somewhere and bought 150 steel, yea woo 
Better than mine. They bought 550 of my steel, travelled for about 10 turns and then got blown up as they entered the guy's sensor range. No battle report, no war declared, they just died. I think once my little war is over I'll send a load of traders out to my colonies and then bring back the steel they have there. One of them has nearly 27k but can't do anything with it. If I had that back at my home planet, I could pump out 3 more arcs.
