I once was planning on switching to BEM but after reading on it and seeing the amount HTML/CSS code you'll need to achieve things that can be done without bloating both your HTML pages and CSS sheets especially when it doesn't take the cascading part of CSS as an advantage; I never tried it since.
@cutcodedown hits the nail on the head regarding BEM.
CSS variants like SCSS help in building proper CSS without having the drawbacks of CSS with variables and such.