I would say in both cases as a leather Hero owner your chairs will wear in very nicely over the next few weeks.
I've used a leather Hero since last August working full time and gaming, so a lot of use, my old chair was a worn out old rocker with terrible posture, so I also got very minor lower back tinges from the Hero for the first day or so as my posture adjusted.
The initial stiffness is real, but it will definitely soften up, the seat first then the back, I set to working on it full time as soon as I got it so it got worn it quickly, but I've done a 14 hour working day before on it and a 65 hour week with no ill effects.
After a week or so of sitting up about 10-15 degree lay back with hips and back pushed to the curve of the chair with a straight shoulder posture, I noticed I was standing a little straighter and even taller in general, so any adjustment to it will improve your back in the long run. I also sometimes slouch a bit forward and sit more mid seat with legs stretched out, you can even sit crossed legged 4 style as there's plenty of room on the flat seat. I sit up straight when typing for work but lean back for gaming typing.
At 6ft exact on the standard gas pole lowest setting there's clearance from the back of my knees to the front of the seat and my feet lay flat on the floor. If you feel the way the chair interacts with your legs is uncomfortable, you can get a shorter/longer gas chair pole very cheaply, that could also take some pressure off your legs or hips.
Either way, you've both still got some wearing in time, it will take longer if you're just gaming on it, but they definitely will wear in to be a lot softer.