There is a reason some products are termed, Core Collection: their fabrication, colorations, fit pattern and overall design hit that “sweet spot” of perfection. Like this (reasonably priced) item. There is everything to like about this product which makes an ideal 3-season LS top.
As for the 50% merino content, this is a bit of Goldilocks territory. Less than that, and there is not enough merino to offset the typical polyester issue: Early Odor Onset. And EOO is particularly annoying to those around you. Spare them!
And avoiding 100% merino content allows a broader comfort range (don’t believe fools who think merino is “terrific” in summer, it’s a (Smart) wool cult that says that given as merino fiber absorbs water (like summer sweat), it releases heat which isn’t exactly what you need in summer.
And 100% merino, once wet, is near impossible to dry in the field. So 50/50 blend is ideal which most Norwegian realists have long known. Further, the poly is “plaited” on the inside, giving a smoother, non-itch feel and drying faster next to skin.
Kudos for the design team here for creating a core winner that should always be in the line. Just change the colors once in a while which will incentivize the 5-Mila faithful to add to their Amundsen wardrobe.