I have noticed that the Smith Machine doesnt realy allow me personaly to squat any heavier than free. I use it becuase I dont have any spotters that are worth a hill of beans and I dont want to get hurt at this stage of the game. As one gets older you can either not train close to failure and use free weights and make very few mass gains or use a smith and train closer to failure. The only way one can train close to failure with free weights is using a spotter or messing up your back when you are alone. Just my opinion. I do recommend free weights when you are younger and have plenty of training patrners.