One of the biggest player power spikes I've noticed is just having two people. The jump from one to two is so much bigger than two to three or three to four. Having one person with the Healing Chem Launcher who can partially focus on keeping both players topped off while then having 3 offensive skills between the two is a huge bonus.
I've run some missions without healing skills and they are definitely harder but still doable. Enemies drop armor kits relatively frequently, but you'll still want to make sure some gear talents are on your side for that one.
How do you guys feel having a third skill per player might impact the flow of combat? How might firefights and encounters be changed with that single addition?