Increases heat 1 cal when wet. Fleece...don't think so
The merino fibers are soft and long, so I don't find them itchy at all. I wear no synthetics, wool and more wool. Merino against skin, and KOM, amongst others outside of that. Ok, ok, synthetic underwear :D
All the synthetics try to compare to....you guessed it, wool. But they melt, stink, clam up, and don't do what wool does.
Combine it with down and I think we have a combo that can't be beat. When it's really cold, I just add down and I'm able to function!! It took a long time to find the magic combo. I'm miserably cold all the time compared to those that don't seem to mind the cold.
I think those of us highly affected by the cold can make a true comparison in gear when compared to the grizzly bears able to go almost naked and continue to function as if 70 and sunny!