Active insulation (proton, nano) vs Polartec Thermal Pro (R3)

Merry Christmas to everyone!

Snowboarder here, I am torn between Nano Air and Proton LT to be used  for snowshoeing/split (most likely more snowshoeing and snowboard on the backpack).
It will be used under a hard shell, so wind protection is not the most important thing, rather being warm if still, and wicking moisture when sweating.
Heard that both jackets are good at keeping warm while providing excellent breathability.

Then I thought I have already a  fleece I love, the Patagonia R3 hi loft, in Polartec Thermal Pro. And reviews are that it wicks moisture well.
So question for you experts: what would be the main difference/issue in using the R3 for snowshoeing instead of Proton / Nano Air?
would the proton/nano breath better? or be warmer?

Thanks

The Proton and Nano Air are the insulation + softshell in a single garment. They are lighter and more compressible than fleece. Beyond that they don't perform significantly better than high loft fleece + softshell (or windshirt) IMO.

I would just use what you've got. 

There's not going to be a huge difference, but a few minors that can be mentioned.  First, active insulation pieces, like the ones you mention, offer more warmth for their weight vs. pile fleece. Your R3 will undoubtably be warm, but I'm sure you'll pay a significant weight penalty.  Additionally, packability in active insulation vs. fleece is much better.  They pack down in a pack or stuff sack mush easier than your R3.  Secondly, I find that my Nano-Air pieces dry much faster when wet than any fleece layer I've owned.  As long as I'm wearing something breathable like a softshell jacket, I find my Nano-Air Light Hoody evacuates pretty much all perspiration, allowing my body heat to eventually dry it out almost completely.

My 2 cents is that active insulations are the next step in the evolution of midlayers but that doesn’t mean fleece is shit. If you’ve got a system that works for you, then I’d use that. I probably wouldn’t buy a new fleece, though. I’d opt for active insulation for all the reasons alpine ice mentioned.