I wrote up some thoughts on Reddit in regards to the Nitro. I hope it helps.
I've been using a few Macpac Nitro hoody's (140g/4.9oz) (Alpha Direct) since they were released in Australia in early 2019. I can confidently say I have put the fabric through its paces and I am quite happy. Its definitely and all season layer in my neck of the bush. From summer to winter I have found a use for it.
I have used it several times as a baselayer while skiing with a rain shell over the top and it was very comfy and warm, it feels quite nice against the skin. I have used it as my only layer while running in the 20s here in winter as well. I mostly use it over my button up in shoulder season, I add a wind jacket or my rain jacket over the top for an awesome combo of warmth, breathability and wind protection. Its really versatile.
Breathability is its strongest selling point imo. It is exceptional. Wayyy ahead of any 100wt fleece or grid fleece I have used. I can leave it on while climbing and feel comfortable the whole time, even when the weather is a little warmer than expected. I find I leave it on during the day far more than my other fleeces. When the wind picks up it definitely needs a layer over the top though. It bleeds warmth quickly.
It dries really quickly. I guess because so much of the fabric is exposed and lofty the fibres have more contact with the air(?).
Its biggest downside is its lack of durability. This is not the fabric to use off trail or even on overgrown trails. It rips easily and gets caught on nearly anything. I have destroyed two Nitro hoody's by taking them off track. The fabric has a tendency to "shrink" each time it is pulled by bushes or caught on scrub. The last one i used off trail ended up looking about 4 sizes too small for me.
Some examples of the "shrinking" effect -
https://imgur.com/a/X5bymmHAlpha Direct gets a huge thumbs up from me. In the right conditions it is just about the most versatile bit of clothing I have used in the bush. Ill keep using it for the foreseeable future despite its durability issues.