Mark, Thanks for posting this. The shirt sounds interesting, and it was pretty cheap, so I purchased one. Below are my thoughts without wearing it out in the sub-zero temperatures we have at the moment.
The fabric is very thin for a knit base layer: .031″. This is the same thickness as an HH Stripe shirt, which would explain a fast dry time. There is very little fabric, so it can’t hold much sweat and can dry quickly once sweating stops. When faced with a heavy sweating rate, I expect it will saturate quickly, but then it will dry quickly after you stop an activity.
The polypro inner mesh layer is somehow bonded to the outer polyester layer. How this is accomplished and whether the bonding process restricts vapor passage through the fabric is unclear.
I did pipette testing on both layers. The polypro layer is hydrophobic. The polyester outer is treated to be very hydrophilic to support its wicking role.
The Air Permeability is 258 CFM/Ft2. This should provide decent breathability and wind protection. Breathability will be way lower than the Brynje/HH Stripe or Finetrack combination. I expect this shirt to be inferior for sweat management to a Brynje/HH Stripe or Finetrack combination for moisture management. This shirt will lack the air pockets formed by the Brynje mesh that enables sweat on the skin to evaporate and become vapor before hitting the next layer, enabling maximum evaporative cooling. It also can’t match the trick of providing some insulation and simultaneous moisture control offered by the Brynje/ HH Stripe or Finetrack combination.
Concerning Mark’s layering. I get the impression that you are wearing your base layer, the Merino or Alpaca shirt, the 120 gsm Alpha Flash, and the wind layer at the same time. If so, that sounds like a lot of layers for hiking uphill at 20F.  My ensemble for that temperature would be long-sleeve Brynje, HH Stripe, possibly 60 gsm Alpha Direct, and a wind layer with pit zips. Once I am warmed up, I would remove the Alpha Direct or wind layer. Of course, our needs for warmth and breathability are all unique.
I will give this shirt a try when things warm up a bit.