About Ina Bauer, this move is not defined by the back bend; it is just a feature that a skater can add for extra effect. Even if a skater has good back bend, that doesn't mean they are good at Ina Bauer.
Many skaters bend backwards in this move, but actually it is not required, they can do it in an upright position. The main focus on the Ina Bauer is NOT the back bend but the quality of edge a skater can achieve while keeping the back leg straight. With outside Ina Bauer, it is not too difficult to do on a slight outside curve, but you need extraordinary turnout in the hips and huge amount of strength to do Ina Bauer that draws almost a circle on the ice, especially without slowing down the speed.
This is why many people call Yuzuru's Ina Bauer the most impressive because he holds the Ina Bauer position the
longest in the field. I have seen no one, be it men or lady, has such a long Ina Bauer as Yuzuru.
Most skaters only keep Ina Bauer position for like one or two second. Yuzuru can do it in 8-10 seconds. Here you can see his longest Ina Bauer he kept from back bend to upright position:
https://youtu.be/Iy7ykIz96m4?t=1m59s