Modern brake systems are open, and DOT fluid is hydroscopic, it absorbs water vapour out of the atmosphere, so performance can degrade over time. Not too much of an issue if you're just doing regular xc type rides, but when long draggy downhills involving heat build-up are included, then the water allows heat to fade the brakes. If systems were sealed, then my six year old M4's wouldn't work 'cos one of the bleed nipple covers has been missing for a couple of years. Since the last time they were bled, I think. My six year old M4 Mono's haven't been bled for about the same time, either, and they work just fine. Both sets still got the original pads in too. If I was looking for an alternative, then Formula or Quad, depending on budget.