Another nice thing to add would be a very slight buff for aliens that work together. Sort of like permanent passive pheromones. It might cut stun time by 5% per alien within 4 tiles, up to 20%. Or it might reduce damage by 2% up to 10%. Something.
It wouldn't noticeably impact T3s and others, but it would be a useful buff for ambush castes that also impacts their play as it nudges them to team up. Alternatively, make it a stronger buff and apply it only to ambush caste aliens.
A lone runner or lurker attacking isolated marines in the backline is all well and good, but I don't think anyone would disagree that they should go down pretty easily when they're on their own. However, if 3 aliens attack a single marine (even 3 runners), then it kind of sucks when any of them can just die to a PB after a missed pounce.
Food for thought.