I made some observations on trading that made me wonder why a trader would ever use his trading vessel to trade!
Once a decent trade route has been found, you can run about 4 times as many trips in a shuttle Mk1 as you can in the fastest trader. I have found that the cargo space is not the limiting factor, Galcreds are. Since there are cargos with high value and low cargo displacement, you can load up to 400,000,000 Galcreds worth of cargo in your shuttle. Once I have this kind of cash I load up the first shuttle, launch a second shuttle, EVA to it from the first, then load it up. Then I give it orders to accompany the first shuttle to the trade destination, e.g. Wraith in Lyrius. When I get there I simply sell all from the first shuttle, EVA to the second and sell itÔÇÖs contents, then return with both shuttles. This overcomes any cargo capacity advantage that the merchies have. The shuttles can evade trouble much more easily as well.
If I was a trader, IÔÇÖd have a huge fleet of Mark I shuttles with crews, semi-permanently moor the mothership to the home trading station and try to keep up with counting all the Galcreds.