Aparently there's rumors that when Engineers are stacked high they actually produce drillers after a fight (when repair rate is at 125%). Walk in with 200 men and walk out with 205, without the help of a thief.
The wiki sets a cap at 100% but like I said, there's rumors. I'll be getting confirmation on it in a day or so and post a screen shot. And I'll post a bug report if the cap is indeed supposed to be 100% repair rate.