Actually, I started to slightly break out after using Studio Sculpt. However, I absolutely LOVE my Studio Sclupt. It's an amazing foundation. Maybe that's why my skin started to break out... I used it much much much more often than my Studio Fix.
Also, my skin does better in general when I use the MAC makeup remover before I wash my face, regardless of what foundation I'm using at the time. Do you use their makeup remover?