I have not used a Marathon Squat Suit since the early eighties. From what I recall, it was a good suit for the time, but I believe that there are better suits out there. Go to
http://www.geocities.com/kory_wnuk/links.html and look for the link to John's Powerlifting Page. John has a good section on equipment.
FYI: I am not sure what the delivery time is for the Marathon Squat Suit, but I know that I waited nearly 6 months for my Marathon Deadlift Suit...something you may want to take into consideration.