I am a forester and the concern on damaging the tree is not so much with the screw in steps if you remove them at the end of every season and rotate your stand locations. The trouble is leaving them in and letting the tree grow with them and hold them. The tree is ruined, useless. Nothing makes me sicker than to see a good tree with spikes, nails, railroad spikes, wooden stand. Hunters pick the best tree for the stand. So, just remove the screw in steps after each season.
As for the ladder stands, nothing wrong with them at all. Sportsman's Guide, Walmart, whatever is the cheapest. A little harder to move, but stable, comfortable and just as successful.