If you equip this you will become a worse healer (lots of better trinket choices), but you make everyone else a little stronger.  I know that this would have been a godsend back in the old 40-man tank and spank raids, but does anyone even use this to great effect in 25-man?

Also, who cares if you can holy nova spam your whole party to give them the buff.  How many times are they going to get non-holy nova healed in the next 20 seconds and would the extra healing on subsequent holy novas even make it a better group heal than prayer of healing?