I did not had luck with superstar kevlar on my Formula RX.
Original formula organic pads lasted half of year (~20k vertical meters). Then I’ve tried kevlar ones from superstar, only lasted about a month (3-4k vm). Although I must admit, breaking power-wise, they were fine.
Now run original sintered for few months still going strong with more power than kevlar ones (mostly on long descends when breaks heat-up and organic ones start to lose bite).
Considering what life I got out of kevlar, the original ones are comparable in price. Maybe I got a bad batch, I have no idea. Some of the guys around here are using them and are happy though.
Update: yeah, this is riding in Alps area, so no major mud. Although these is some now in winter, not nearly as much as in UK I would imagine.