Actually I just got hit by a Dwarf trying to run a SB strat against me, a few days ago. Luckily I had spent over a week doing nothing but Bals in anticipation of Jets testing my invincibility.
We managed to kill : 1405 Shieldbearer 668 Hammer wheilder 2208 Axe Man 0 Runner 1162 Light Crossbowman 0 Heavy Crossbowman
But we lost : 348 Catapult 0 Infantry 0 Militia 0 Rider 0 Rock thrower 617 Balista
I haven't done the calcs of the resource cost on that. It does sting though, several days of build time to replace that. But what I gleened from it is my weakness to SB. I'm sure my magnificent long range vaporized 100% of whatever units weren't protected by the SB, those SB saved units then went on to melee and caused all my losses I'm sure. Nothing much I can do about that, except keep pushing Bals ahead of my Cats to make sure I have something left to defend in melee.