As always, I appreciate you taking meaningful real-world measurements!
I have loved merino wool over the past decade for its low-odor properties. It definitely doesn't wick as fast as polyester, but I feel comfortable even when there are some damp spots on my shirt. It would make sense that adding some polyester, maybe a third by volume, could improve the wicking ability over pure merino. I don't see the point in weaving a fabric with just a small percentage of merino wool.
After reading a review about the Rab MeCo in another backpacking magazine, I purchased their 120-weight short-sleeve shirt. The MeCo is a blend of 65% merino wool (the "Me" part) and 35% polyester that contains tiny particles of charcoal made from coconut husks (the "Co" part). One would hope that the charcoal would absorb odorant molecules, and I can say that it really works. After a long day hike, I'll smell some odor when removing the shirt. After letting it sit in my tent overnight, the odor is gone. It's really impressive. It does wick better than pure merino, but not as fast as pure polyester. I have just worn this shirt a few times, so I can't comment on long-term durability.
My 120 g/m2 Rab MeCo shirt in size L weighs 4.7 oz, while my 140 g/m2 Icebreaker Superfine merino shirts in size XL weigh 6.0 oz (the XL is a little looser fit). For another data point, my Icebreaker 180 weighs 7.5 oz. I prefer the lighter-weight shirts for hikes on warm days.
I also purchased the Rab MeCo 120-weight long underwear, which were difficult to find in the US. In size L, the waist band before stretching is only 24 inches. It does stretch out to the 34 inches that I need, but they are way too tight.