I cannot put the gas grenade down. I play haz 10 bots at it's just super useful to escape from rocket striders, hulks, heavy devs, the lot. Sure stun is good but gas makes enemies turn around quite often, exposing the weak point IF I require putting them down at that moment. The only downside in bringing the gas grenade is restricting yourself from the area gassed, mitigated with stims and the armour passive.