And that penalty of course applies only when you can not draw LOS.Yes, you can choose to fire directly or indirectly with a whirlwind.
I suspect most people fire indirectly is because you can keep the unit behind large cover and out of sight from pesky long range anti armor fire. The longer it lives on the table, the more damage it could dish out. The only drawback is not being able to apply the BS skill to the scatter dice.
I'm personally fine with that as it's only got a 24" range in the first place so not muched gained. However the pinning with -1 Ld would be nice.I saw the other day that in the space marine codex the vindicator can be fired as a barrage weapon. thats awesome but guess what. The chaos vindicator cant be fired as barrage. explain to me the difference GW. but yea i like whirlwinds, the ap isnt awesome from what i can remember, but its all about wounds.