You're right, performance is a reason to upgrade. I'm satisfied with mine, but it could be better. Whenever I use my wife's 6s+ I'm mildly shocked at how much smoother and more responsive it is. I don't think it's enough to get me to pay $769+ to upgrade, but it's still a potential reason to.
The headphone thing annoys me enormously, but it probably won't be a factor here.
The headphone thing annoys me enormously, but it probably won't be a factor here.