I agree 100% on this . I just left my 6+ for the 6+s and wow I'm very happyI think the 2GB RAM, Touch ID improvements, and camera improvements easily make it a worthy upgrade. I went from the 6+ -> 6S+ and it feels like a completely different device.
The iPhone upgrade program also made it an easy decision. Especially if you have a device to sell.
I agree 100% on this . I just left my 6+ for the 6+s and wow I'm very happy