I had a PWM BJ Box
mod and the output was smooth and powerful - rated to 250w - with no "rattlesnake" effect at all. The box did produce a whining sound when fired, which is considered normal for that
mod.
Point is, PWM is not an inferior or outdated method of powering a
mod. If done correctly it is (or seemed to me) just as effective as any regulated mod I have used, including my Hexohm mods.