Poor Heel Support
I took a gamble on these based on my experience with the heel support giving out with my Evolution Mids. I needed a light, ventilated trail runner. I currently have the Treksta Kobra II and Evolution GTX Mid. These are comfortable. I have a flat-wide foot that is near impossible for me to find a shoe that I can say is comfortable out of the box (I usually find the lesser of the evils and pound it into submission with my duck foot). The to box is roomy and never had issues with hot spots, heel slip, or discomfort. I used these for Colorado mountain trails as well as work (on feet 9/10 hours running around/standing).
However, after only a few months I noticed that, like the GTX Mids, the heel support seemed to give way. I noticed that my right heel was essentially collapsing into the midfoot and laterally outward. This started to make the shoe uncomfortable and I had to return them. Yes, I took a gamble after having the problem with the GTX Mid hoping it was an isolated issue. I didn't get the GTX Mids from Backcountry (big mistake) so I'm now stuck with them. I have contacted the company regarding this and apparently this has been communicated to their development group (whatever that means). The good news is that I've put my Kobra IIs through a ton more abuse and are still running strong.