I initially thought this, but the Gargant counts as 20 models thing is a myth. It's a Sons of Behemat Alliegence ability. So my Gargant stupidly only counts as 1 model (I would love for you to prove me wrong). Loosing the CP aswell is rough, those Merc rules are rough on FEC.
He is however a wonderful distraction. And gets targeted over the 9 flayers and smash bat. He is also pretty consistent with damage, maybe better then a ZD. And doesnt get any worse till it's taken 12 damage which normally would of finished off one of our monsters.
Adding the ghoul king, is a good idea, but would mean dropping the 9 flayers to a 6, and the 9 fits round an Ironclad nicely.