Yes I just tested on Atlantic, using a composite bow drag slayer, I was hitting a greater dragon for 34-42 average without stone form, and exactly the same with stone form : 34-42.
The damage increase from stone form works the same way that the horrific beast damage increase functions in that it only affects melee damage. It does not affect ranged damage at all.
But the casting description is still not quite right, we don't have "cast speed", we have "faster casting"
I do agree that the stone form buff icon should display with "-2 faster casting" as well as the "+X% melee damage".
I have submitted a problem report into the system on the stone form buff icon text as well as the horrific beast buff icon text.
