Acopa is a great company they were helpful when it came to returns and finding the right size. In the end I down sized 1 1/2 sizes for the perfect fit. I have owned several pairs of climbing shoes such as the 5.10 mocc.'s, 5x's, dragons, muiras, and the testarossa's, to list a few. All have their strenghts and weaknesses. But the merlins have proven their ability to me. The new technology allows you to edge and smear on the outside edge like never berfore it is absolutly incredible. It draws power to the big toe as well for precise stepping. I think the rubber is as sticky as the 5.10 stealth! The only draw back is the heel could have some improvements made for hooking. But its still far better than most. Whether it be climbing 5.11 cracks, or 5.12 sport, evan hard boulder problems this shoe does it all. I'm glad I bought mine.