I don't like merino past the base layer, yes it pulls moisture, but it holds it in my experience. Using fleece/active insualtion seems to work well with merino under to help get things dry, while keeping the funk down. I can toast a sythetic piece like the Avro in two days, have pushed it to 2.5-3. I like merino for backpack hunts and generally like how it feels next to skin more. I've had merino based mid layers and they haven't been great apart from being quiet.
The ambient really ended a lot of layering system fluctuation for me. I use it for everything past my baselayer instead of a fleece, right or wrong. I've used the SG merino stuff and had good luck, went back to that for a baselayer top this year.