As Shadowlord said, a central position works wonders!
They are neat on the flank too, but I think I made it a bit easier for Shadowwolfs captasus to get mine then (Well, to be honest, only his Pegasus made it through, the captain was blasted from his steed, but due to Shadowwolfs usual luck with the dice, the pegasus somehow survived the withering volley of pistols and helblaster).
However, when I used it as center - flank lynchpin, parked in a cementary, it caused all kinds of mayhem to my friend Toms undead. Hence why I dream of two helblasters on occasion.
But that would mean my pirates can´t take any ogre mercs... and my Stirlanders should not field two...
Despite the fact you have to use the BS of the crew to get hits, and despite it´s tendency to blow up, when it works, it creates mayhem and your opponents gets scared by it´s mere presence! Shaving of -3 to their armour saves helps a lot aswell!