The only synthetic layer I'm fine with is the Patagonia Capilene.THIS!!!! Look for smartwool and/or Icebreaker. Look for them on bargain sites. Go ahead and buy used. Nobody cares and wool doesn't stink like the fake stuff. Buy a used Patagonia, Arc'teryx, etc. breathable shell on ebay or any bargain bin. They're out there. Then use a tech-wash (REI) to get the material realigned. I'm still using an Arc'teryx shell from 15 years ago.
Today's wear for me is a Patagonia Capilene 3 Polartec with an ultralight Arc'teryx windbreaker. Both acquired extremely cheap second hand.
Another useful function of Merino Wool is with Snowboarding. We commonly change in the parking lot, and when it's time to leave after a night sesh the synthetic is very breezy and chilly when you pull the jacket off. With Merino, you just don't suffer that chill the synthetic brings. Just pull the shell jacket off, and hop straight into the heated seat for pure warm and cozy pleasure for the long ride back.