It is often too warm to hike in two layers of Capilene and smartwool here, but I put them on like you when I get to camp. I prefer synthetic as it dries more quickly and I think Capilene will breath a lot better, similar to CoolMax.

I might hike with two layers if it were really windy at elevation or where the temperature was falling close to 32 during an ascent. Happens quite often over mountain passes or during shoulder season here in BC. If wet and cold, I would probably stick with one layer and eVent or my windshirt.

Lots of good experience informing everyone's posts on this topic, have to buy some Capilene on sale from Patagonia and take it on a shakedown hike!