[Krsqk]

If you don't want a dedicated PDF ship, you could use these to protect important ships in your fleet. They probably won't go off at seekers targetting other ships, thus (theoretically) increasing that ship's chances of survival. Of course, the overlapping PDF thing probably isn't bad, either. These would probably work well with the bait and charge tactic of planet attack. Send one ship in to get WPs to fire, then send the rest in next turn. The self-defense Versions should deal nicely with any missiles left after two turns of good solid planet-pounding.

Oh yeah, I've also used these on WPs on new colonies. It's not worth the expense to get range 5 PD coverage when range 1 works just as nicely to protect a single target.