I've never tried brainwavz, but the PFE 122's are not bad with D&B. I do listen to a bit of that n dubstep (never used them amped as my Fiio is stuck behind the radiator lol). To myself i find the bass reasonable. Very clear (And im just wearing them in), using the grey filter tips.
They give a good representation of the bass, but prefer my Sennheiser IE7's if you're a nutcase of a bass head. All that said, i would wholeheartedly recommend them. PFE's seem well built too. nice thick cable, superb fit (esp with comply tips included). PFE's for me (Though i cant directly compare)