The only reason whatsoever to be running a drop pitman arm, would be if you had a different style steering setup (i.e. crossover steering) as oppose to the stock Haltenberger design.
The only point you'd need to be running a drop pitman arm on the stock TJ Haltenberger style steering, would be if you were at a very excessive amount of lift (I'm talking probably 6" or more).
At 4" of lift on the stock TJ steering, you need to be running the stock pitman arm. If you run a drop pitman arm, you will run into all sorts of drivability issues.
And
@Ahoragi is correct, with the Currie Currectlync, you should not be running a dropped pitman arm.
Like Jerry said at one point, it's all about simple geometry.
I think we may need a pitman arm FAQ!