OK, got the R1 full zip Medium fleece shirt and have tired it for a few evenings out. So far these are the things I have noticed:
1. This is a very thin, technical piece: when you hold it to the light you can see right through it. If there is a breeze you can feel it but without a breeze it is incredibly warm.
2. Construction is top notch and is VERY comfortable for a close fitting piece; I could wear this right next to my bear skin it feels so nice.
3. Super easy to slide my Marmot medium size Essence jacket over due to the smooth finish on the outside of the shirt.
4. When I zip it all the way up it is still super comfy and I can zip it wide open for cooling.
5. packs down WAY smaller than the old thick wool sweater... verdict is still not in about if it will keep me warm enough when the temps drop
In 2 weeks I will give it a full comparison against the "old wool sweater" and let those that have been on the fence about replacing their tried and true warmth layer with the new technology in on what i find.
Here is a closer look at the fabric from the inside of the shirt:
Patagonia R1 fleece.JPG
Stay tuned.