I got my wife a 6s RG. It is perfect size and weight for smaller size phone, but 6s+ is different story, compared with 6+ I already had.
One thing it really bother me is Apple squeeze in heavier 3D Touch display in new heavier material case. Which result into a larger phone I think is just too thick for additional case, and too heavy to one hand all day long with good protection case, at least compared with 6+, when I played with it in store. I know a lot of people is feeling fine with add thickness and weight due to 3D Touch and 2G memory are both big deal improvement, but once 7 is out with thinner, lighter, maybe even narrower if Apple does go edge to edge display, they will think how did they handle 6s+ for one year one handed.