If anything I would prefer to see the class removed entirely. Leave such matters to the Merchant class after all.
Trader class, even with the features described here would perhaps be a bit too much of the same and, unless you just like hoarding lots of gold and things, not interesting enough to keep altogether.
This does make me think of a special character type like advies for the trading game or Merchantmaster adding lots of other features.
However i think this would just make things bigger and more complex to implement and potentially taking away the whole strategic importance of resources depending on how it works in realtion to the normal characters.
Because even without direct influence on other mechanics, tradable resources will dramatically change the strategic importance of owning certain regions or having friends own it.
The way supply and demand works on well spread resources will make resources very profitable in case one has excess to the markets in different region types/areas.
Realms will target specific region types based on their needs instead of just the richest regions, because the excess to those markets will eventually make more gold then the extra gold gained from taking the richer region instead.
Wars will be fought over a part of a mountain or forest that at first had no strategic importance because of their little food/gold production or strategic location.
Friendships or alliances could be formed over a mutual interest in sharing each others markets until they discover that one of them benefits more then the other (trump vs china anyone?
).
Realms wouldnt be able to ignore resources, but individual lords or knights can if they don't care, however if they do choose to trade they will be able significantly increase their income.
The fact that this works on every level(realm or knights) and especially that it makes those specific regions more interesting that are now absolutely not, creates many opportunities in the game and new dynamic locations of importance(as region shifts ownership or certain resources are traded more or less, strategic importance changes).
