We (the administration team) have had a large number of discussions relating to the addition of a "Trading" and other channels in the chat, however our chat system is currently much more complex than just the general and local channels; as you explained we have the world channels. This would mean that adding other layer of channels for people to talk in, it would all become very confusing for players, who will have to keep switching around in channels.

The main issue we had with it when discussed though was the idea that people would end up using the trade channel as their general talk channel just to get it to stand out in the main chat. Plus there are people who don't like to talk in the localised channels and switch back to global anyway.

Plus much of the trading area is "unmanned" meaning that shop owners tend not to actually need to be in their shop to sell items, by using the chest shop you can be anywhere in the world and still sell/buy items. Would these people then also be able to hear the trading channel in case anyone in the trading area needed help?

Your best bet is to just use the local channel when trading in the Trading District, it means that only those near you hear you, but is easy to switch back into the general channel if required.

Whilst I like your idea and it is a good suggestion, because of our current world channel system, and people not being disciplined enough to stay in the channel they are allocated to; it wouldn't be easy to implement/maintain.