This is my 3rd woolx shirt. I bought size L, in Rose Petal color and it is a lovely color; definitely a rose pink, and not just pastel pink. Two years ago I bought 2 Remi shirts. I am 5'8" and around 165 lbs. I am older, and did not want my shirts to fit snugly. I think the Mia fabric feels softer, though both are very nice quality. The Mia is *very* comfortable against my skin.
The point of the v-neck is not too low; I am planning to take it on a trip to the Middle East and it should be fine for areas I need to dress conservatively.
I bought the Remis in X-L because I wear them both on their own and sometimes over cotton shirts. Possibly I could have gotten size Large; but the Mia fabric seems at least as stretchy as the X-L Remis and I wonder if I should have gotten size M for the Mia. It looks fine on me but I can pull on the front and it stretches enough to fit someone extra-large. The Remis are not like this; they are 2 years old so perhaps there are slight differences in the fabric though the content on both shirts now is identical.
I am thinking of getting another short sleeved woolx, and may try the Liza in medium, which is a loose fit. The Mia has far more colors, but the Liza might be my sweet point, size-wise. Hope this helps you assess sizes! The shirts are wonderful, I am very happy with all of them.