When you get the first sniper rifle you've finished the game.
Nope, didn't worked for me. First, because I have only one sniper in my team, never more and second, because the enemy every once in a while was able to overrun me with mass. This combined with the new aiming system makes it quite harder than before. You can't really do headshot, headshot, headshot,.. anymore. Additionally, they now - for the very first time - effectively used sniper rifles and grenade launchers as well, which in return - finally - made me use my own grenade launchers and mortars much more often than ever before (this is a good thing). So even though the difficult isn't astronomical higher, it at least brings me to the point where it is more efficient to use a broader variety of weapons.
I mean, did anyone ever used grenades or grenade launchers before? It was just inefficient, you had been better off with headshot, headshot, headshot.
Ah, while I am at it.. with the new aiming system, even Ira wasn't useless to me anymore in the beginning. She wasn't what I'd call "good," but she also wasn't the most bad thing in the game, simply because the other mercs in my team couldn't deal headshots anymore all the time.