I lost 3 stone in 4 months, losing my first stone in my first 3 weeks on EE. I wasn't even exercising at that stage. I put it down to the complete change of my diet, my diet before was terrible so moving to a low fat healthy eating plan obviously kicked things off in a big way.
It has taken me longer to lose the last 9lbs, but that has been down to me, not SW. I have been more relaxed and have had a few weekends off plan. I've still lost though, just slower.
Up to the beginning of May, I think my average loss was 3lbs a week.