I've got the 230. I love it. As was mentioned above, though, it has a fleecy, polyester inner lining. I'm curious how that will handle the stink factor. Pure merino is the way to go if you're primarily concerned with smell. Also, while the 230 is warmer, I'm not sure that there will be a major difference. Remember, KUIU is built to be layered. They designed the 180 stuff to be first layer, followed up with the 230 in colder temps. I myself am wearing an Ibex brand pure merino 190 baselayer with the KUIU 230 over that (I'm treestand hunting in WI, though). So, my suggestion is to go with the 185, pure merino as your first layer. As far as KUIU vs. Sitka, I like both but have gone to KUIU. But when it comes to merino vs. synthetic, no contest: merino all the way!!! Hope that helps!!!