Yeah, I've noticed that problem too. You could fire it, which could take out a lot of the competition, but that would leave you with a dinky pistol against what I will from now on call Nine ball. Do you want to take Nine Ball on with a pistol? Because I kind of doubt it would kill him, even with the atrocious damage that may or may not be done to it.
Your stuck in a situation of fire or don't fire. If you fire, it will undoubtedly piss off all the mech still alive, and there is assured to be a few left. If you don't fire, you can't do much else. While I dread saying this as it hurts my chances, your best bet might be saving it until the enemy mech is dead, or close to death. Its a bit of a Russian Roulette, with a bullet in every chamber but too many heads all around.
I personally think we should super focus on this new mech because its an unknown. To put it shortly, we won't know shit what it could do. It could be both super fast and have very heavy armor, which would make a large portion of us piss outta luck. It could be even more destructive than the Destroyer, if such a thing could be possible. It might be able to beat out Fat Man in a bass blasting contest for all I know. Simply put, we don't know anything about it, and that's dangerous. We know how dangerous the Destroyer is... But we don't know how dangerous the new guy is. Its a question between facing a machine gunner you know, or a sniper you don't know. Both are horrible, but one is in my opinion much worse.