I have warn both. I prefer the lightest weight merino for warmer weather, as it does better with odor control. I will switch over to peloton for a 2nd layer anytime the weather drops. I stay warmer and dryer wearing synthetic base layers. I perfect a Patagonia base layer with Peloton as the weather gets cooler in the rifle seasonsAny Kuiu owners who can weigh in on whether you like the Synthetic Peloton or Merion base layers better and which is best for a hot vs cold hunt?