I have been experimenting with different base layers for a hunt in the mountains of Wyoming a month from now. I tend to be hot-blooded and will sweat plenty when walking hard uphill. The place we hunt involves a walk of several miles and gaining quite a bit of elevation to get to where we glass at daylight. I always end up drenched by the time we get walked in, and then I have to dry off before putting on extra layers to glass. I haven't experimented yet with the new moisture wicking base layers and wanted to see what worked for others before dropping $20-40 per pair for tops. I want something I can wear under a long sleeved shirt walking in that won't cook me, and later I can add my jacket and down vest for warmth. Color wouldn't matter as it would be covered. I also carry a heavy polypropylene turtleneck in my pack in case I get cold, but haven't yet needed it.