I bought a Pro-Ski because of the lower price. I've only used the Skiers Edge on a demo basis for a few minutes on two or three occasions.
The Pro-Ski is heavy duty, quiet and will give you a good workout. It does work a different muscle group than a treadmill or lunges. I simulates the older style skiing technique that used more up and down motion than today's more edge oriented approach. Yes I think it will make you a better skier - primarily for the overall exercise benefit and to a much lesser extent to any ski specific training.