If concerned about the durability of merino, consider the merino/synth blends out there. Patagonia’s own merino line is actually a blend with Capilene. Icebreaker has started blending most of their line with poly as well. Arc’teryx and a few others are using a merino strand wrapped around a thin nylon core, which seems be better-reviewed than the poly blends for durability. (Check out their Satoro for a good example). I’ve scoured the net wide for reviews on just about all these products, trying to come to some conclusion, although nothing seems to work miracles: the blend fabrics are predictably somewhat more durable than pure merino, depending on weaves and other quality factors, yet don’t reach the durability of pure synthetics. They do seem to hold up well in the stink department, apparently.
The best-reviewed blends for durability that I’ve come across have all been nylon core products. Icebreaker has a really interesting fabric called Cool Lite that also blends Tencel with nylon and merino, and seems to have the best durability of all other blends, but they only make it in light weights for “summer” use – they do have a hoody though!
The most interesting to me as a Cap4 replacement was the Patagonia Merino Air Hoody, a 50/50 merino/Capilene blend of heat-exploded-fibers for more loft-per-oz. It’s currently on close-out (great if you’re an uncommon size, but Mediums are sold out of this production run unfortunately).

