Like Dgraz said, the Archer's ability to fire into melee is huge. They're one of the number of models which (in my opinion) are of unmatched benefit to Ten Thunders Brew Master over Gremlin Brew Master.
BM can lock models down and effectively (or literally) paralyze them in in attack range, so being able to then shoot them, with no fear of clocking your Master is a great ability.
Also, and I could be a little bias as a Gremlin player ;P , but I'd rather have the push trigger on defense than the damage: A push lets you escape melee and shut down a charge if you can cheat in high on the first attack, plus the obvious benefit to positioning your archer out of combat to take his next shot. A negative twisted damage is a little treat if you can pull it off, but it's not as reliable as moving your model to make a better attack in their own turn. But like I say: Gremlin Squeel ftw ^^