It is no problem at all, i love the iPhone 5 design, and prefer it to the 6.
I'm not refuting either claim, each person is entitled to their own opinion. The 6/6s design is my favorite. But I have heard from a few of my "non-techie" friends already, "why would I get that? It looks just like my old 5/5s."
What I'm saying is, I'm wondering if the old design will have any sort of impact on the average consumer (i.e. people who mentally tune out whenever they hear words like "RAM" and "processor" because they don't care), since everyone has been conditioned to expect the "new iPhone" to look "new." But.. it is the only 4-inch smartphone option right now (and arguably the best), so in the end it would have to come down to how bad you want the smaller screen size.