Barry, that is the most common question/assumption that people have with MGS - is that because there is "no turn", you will lose distance. This is absolutely not based in science or fact, but rather on the principle that since all the best golfers in the world use a turn and rotate swing, it must be the correct way to swing the club / generate distance. Just free your mind from those 346 books' teaching for about five minutes and consider this.
MGS has a turn, but you turn your shoulders/torso before you swing. This sets or locks the glutes and lower body in place so that IF you keep the set as you swing, it facilitates the firing of all the muscles at the correct time. And because your feet are flat at impact, you make better use of ground reaction forces, finally because your body mass is better focused through impact, you get power from this also.
With the classic golf swing, there is more SEQUENCING and TIMING involved, and the action is more through the ball. With MGS, you set everything in place with the torso twist, take the lead arm up, drop it back down - keeping your posture - there is no weight shift in the traditional sense, and no hip rotation, and with MGS the action is AT THE BALL.
Having said all that, Kiran has a nice write up on her blog about why MGS works: http://kirankanwargolf.wordpress.com/mgs-howwhy-it-works/
Also, you can watch this video where I make three different type swings and note the club head speeds. I now have virtually the same club head speed and distances with MGS that I had with my more classic Blueprint style swing. if you want to hit it more accurate and with a draw, MGS is the place to be, and once you learn it, I think you will hit it the same distance. here's the video:
Initially, I think because the action is unfamiliar, and you are getting used to it, you will experience a slight loss of distance with all clubs. I know I did, and others have reported the same. But once you "get it" and understand how to make a correct MGS move, you will hit it the same distance, and wonders of wonders, even hit it farther. Your contact will more flush and centered with MGS too, so any slight loss of swing speed is often made up by a more solid centered strike.
My driver club head speed initially was about 5 mph slower than my normal swing[/embed][embed]