I have yet to find a map that can tolerate proxy mines. Even in the biggest maps like Nostromo and Jockey they're annoying, mostly because as the alien you have to maintain momentum. When I suddenly hear that mine's beep I know it's too late to change direction and run right into it. The regular grenades and frag grenades I don't have a problem with, it's those damn proxies everyone loves to spam.

As for the predator pistol, among high-skilled players it's generally considered a cheap weapon against aliens because: A) the rate of fire is so fast; B) a direct hit will instantly kill an alien; C) no charge-up is necessary; D) the weapon deals moderate splash damage; E) the projectile is relatively large and travels in an arc, meaning it covers more of a vertical axis than a straight-shooting projectile like the shoulder cannon and speargun; F) a fully charged predator gets about 15 shots with it. It's a very deadly short range weapon. As you know, the alien has to get up close to do damage in the first place, it's very hard to bring down a pistol-using predator as the alien because it takes one pistol blast for you to die, but three fully charged tail attacks to kill the pred. I've witnessed highly skilled aliens get taken down by a first-time predator with the pistol.

I agree, though, that on coop mode you can enable everything (I still prefer to go sans disc, though) as long as friendly fire is turned off. :)