If you put a weight stack on this, is anything needed so as to not leave a permanent compression in this flooring?

Depending on the weight and how long the weight stack is on the floor determines if a permanent indentation will occur. For most home gym installations, a weight stack on our 8mm Strong Rubber Rolls won't have a permanent indentation. For commercial installations, it is very likely there will be an indentation. There really isn't a great way to prevent a weight stack from leaving indentations. You could use furniture sliders, but you run the risk of the weight stack being unstable.