What would be really cool would be if you could, instead of having other ships dock with yours, have a few fighters which can be launched at any time
A comment about the money side of the capship deal:
If you could buy capships, why wouldn't you be able to buy those huge trader ships? From what i've seen, they can hold about 10000 units of cargo.... so you could make around 10 million credits per run. Pretty soon everyone would be flying around in a huge battleship with around 50 million credits extra to play with.
The whole thing could probably be evened out by
-making the traders really weak (no shields, only one turret slot for all of the weapons) and by amking the extremely likely to be attacked (think about it, it's unescorted and therefore an easy target)
-disableing cruise engines on capships, so that they can fight, but they can't explore or do much else.