Assuming you are hunting in Natimbi anyway, this is a rather nice bonus for killing stonemites along with your tureptras and hynids.
Comparing it to the Qeynos Badge of Nobility tho (QBoN has a little less AC, more hp/mana/endurance, see invis effect, and no req/rec level) it seems a bit high on the level ranges.
If it were reduced by even 5/5 rec/req and the drops moved to creatures similarly lower (yes, would have to be in another zone), it would be really great.
As it stands, the QBoN stays on my characters. :) All of them get it since it is one of the most interesting quest series in the game. .. arresting NPCs, playing a board game with rats...