Yup. iPhone people don't much experience dealing with large format phones. I just came over from the Android world. The 5 has one third as many pixels to push than the Plus combined with lighting up that much surface it's going to mean you have battery and processor issues to juggle. I remember the last phone I owned as small as the 5....it was the Droid X at 4.3 inches. It was released in 2010! So you have 2010 era screen operated with a much more modern processor. Unlikely that will happen again anytime soon.
I want a 5s form factor with 6s specs. Well see how unlikely "unlikely" is.