I tested the MIX MASTER 2 WATERPROOF in a 50k trail run (Chuckanut 50K) and they held up beautifully. The trail had sections that were very steep going up and down with at total of 5000ft of elevation; the traction and the lightness of the shoe provide good control when descending the steep trail quickly. Also, the lightness and solid stability/structure of the shoe provided support climbing the steep terrain. In addition, we faced torrential downpour during the run, but the shoes performed well in the muddy and slick trails; there were some slips here and there when conditions were extreme (smooth, steep rocks with a muddy surface). The waterproofing of the shoe worked very well and held up during the 1st have of the race even during very heavy rainfall. It wasn't until the 3rd or 4th hour into the run that water started seeping in. With the low profile, heavy rain, and (eventually) ankle deep mud and water puddles, that was to be expected. Only slight issue is with the breath-ability; on warmer days breath-ability or lack thereof is noticeable. Overall the MIX MASTER 2 WATERPROOF performed wonderfully, giving great support and nimbleness to allow me to fly down those steep trails with solid control. The waterproofing is great (and if there is a choice between waterproofing or less breath-ability, I’d take waterproofing). Would definitely recommend and they provided significant benefits in the trail run.