In my experience, expeditions are useless unless sending maasive fleets. Sure you take a risk of losing but you also have better gains. I was using light fighters in missions with 10,000 and 20,000 and in 8 trips gained 4,000 ships. Then I tried the same thing in another system and lost 3,000 ships. Some systems have good returns and others dont, but unless you are sending thousands at a time, it is pointless!