If it hadn't been for the race mission, I'd have gone all the way to the Anubis with my clydesdale. I got some pretty good results using that against the Rhinelanders(I used it in the rescue sinclair mission, where the two defectors show up to kill the battleship). Freighters aren't any more difficult to finish the pure combat missions with, as long as you're a fairly decent evader. If you aren't prepared to go juking and turboing all over the place, a freighter is not your ship. Otherwise, it can be one of the best; sometimes those AI's drop a lot of loot, especially over the course of a long mission, and it can pay to use a freighter for some of them. Just be sure you've loaded up the best shields, a good thruster, and a superior pack of countermeasures.