Raid charts are added to the GuildStats.NET client as of version 220.127.116.11 adding the ability to view in a grahpical way how much DPS/HPS was both taken and recived for your group/raid. This feature off course follows the currently selected Encounter and you can open multiple charts for comparing against multiple players.
These charts are open from the Stats tab
There are other types of charts you can use: Real time and Player
You can click on Damage done | Damage taken | Healing done | Healing Taken to either hide or show them.