The general is clearly the weakest upgraded offensive specialist. The problem is that when it is most effective (early game) you don't have enough specialists to make good use of the global ability. In the mid to late game phases, it is generally ineffective. This is because you are dealing with armies of hundreds of drillers...who cares if you lose 10? I understand that you can send multiple subs with specialists to amplify the effect, but you are taking the risk of losing a specialist for a minuscule gain. If you are facing an army of 200 drillers, a thief is much more effective for a single hire than a general.
On a side note, a lieutenant is not a bad first hire. If you don't have any better option, this is a good one to take. The speed boost makes a big difference and the 5 driller kill bonus is not too shabby early game.
I propose a small buff, perhaps increasing the number of drillers a general destroys to 15 or so?
What does everyone think?