First the good parts: these shoes are really comfortable on your feet and have excellent grip (even on Sandstone) for scrambling or non-technical climbing and rapelling. However they are not good if you have to hike through sandy areas, and, are not durable enough to handle typical sandstone slot canyoneering stuff.

After one weekend in southern Utah I had worn a hole in the outside of both shoes (near the protective rubber and orange logo). As for the sand part, much of the hiking done in Utah canyon country starts and ends with a sandy creekbed or riverbed, and the mesh on these shoes do nothing to keep the fine-grain sand out. Yes, you will get some sand in your shoes or boots no matter what you're wearing but we're talking about stopping every quarter mile to empty shoes and socks because the sand is "mounding" inside your sock. :)

If I were Merrel I'd name these shoes something like "Colorado Cross-Trail" or something like that, to give the proper impression they're great for typical dirt / rocky trails and for boulder scrambling and non-technical climbing. For very sandy areas you need something with a finer mesh or some kind of breathable barrier on the inside.