The combat missions you can take on pale in interest compared to the fun of having a big cargo hold and exploring all the new systems looking for that perfect combination that's going to make you a millionaire. And genrally, I find Freighters can hold their own. I do make sure that at every new place I discover that I check the shields, guns and turrets they have for sale - equipping your frieghter wityh the right stuff doe smake a big difference. I'm using a Drone at the moment and unless I'm jumped by a huge number of enemies I always take one the fight - copious use of the thrusters and chase the bastards down. I tend to use the Freighter as a fighter, but go to turret view everytime I'm about to dock with something.
I was raking in the money doing Optronics runs from Honshu to Ruiz Base in Omicron Beta and then hauling Aien Organisms back to New Tokyo, but then I went and plundered a shipwreck that must have beenthe "property" of the outcasts and bam! - I went from neutral to hostile with them and aren't welcome around that neck of the woods anymore. You don't get to have that kinda fun just sittign around bases in your fighter and doing the missions on offer.
Real men haul cargo, don't let anyone tell you differently