A while back I started thinking about why having stone throwers always deviate made them so ineffective. It occurred to me that both the problem and the answer lie in the 2d6 bell curve.
By increasing the modifier, and so moving the hits into the taller part of the bell curve, the stone thrower becomes progressively more effective.
And it turns out that at 2d6 - 3, it's similar in effectiveness to the 50-50 "dodge" save:
The only down-side to this is that the maximum deviation is now 9
inches, so the likelihood of the truly comical mis-fire is reduced.
My hope though is that this gives stone throwers a distinct niche without the worry of them being over-powered. They will be highly variable, and very effective when they don't deviate by much (and hence might seem over-powered in individual games) but in the long run not reliably good. So quite good orc-y weapons, and seemingly worth trying in a game or two!