I'm about 17 stone kitted up and run an M4 front and X2 rear combo, they have been great (powerful, reliable, great feel, easy to set up, genuine pads cheaper than my old avids by £5 a time too), when I was looking to upgrade(fed up with continual tweaking of avids) the quality of the hopes engineering just seemed so much better than the formulas, hayes, maguras etc, and whilst mags say they are down on power I've always felt that they had lots in reserve and I wholeheartedly recommend them.