It is nice to be able to sell while you are away, but you need to keep something in mind. When you are selling from your vault, people HAVE to buy from the broker, with a 20% broker fee. When you sell from your own inventory in your house, people can come to your inn room, and buy directly from you, with no upcharge. So, say you are selling a coral for 18g from your vault. On the broker, it will be 21g60s (after the 20% increase). That means that someone selling from their own inventory could sell have it up for 20g (2g more that what you have it up for), and theirs would be cheaper, since someone could go directly to their inn room, and avoid the 20% broker fee.
While this is not really an issue with cheaper items, once your items start to go for 50g+, it becomes quite a large issue!