It's an interesting jacket because in its current guise I would not buy it - it does not fit me, I don't like the pockets, and I don't want a hood. That's because I ride a road bike and don't tour. However, for some people I think it could be great. If Paramo made a genuinely tight-fitting one with conventional rear pocket and no hood I would definitely consider getting one for winter road riding and maybe commuting: the fabric's ideal and more suitable for cycling than most winter jackets that are either not breathable enough or not rainproof enough. Go on Paramo, you know you want to!
Yeah, fleece all the way for me. If you've a windproof layer with you too it's only really packsize and about 150 g that you are saving. Hiloft and gridded fleeces are amazing. I got through -20 C ice climbing by swapping my normal fleece (Eider thing, but basically an R1 with full length zip) for a Rab boulder one (Thermal pro).
Fleece is more durable, cheaper, deals with sweat better, and feels nicer than insulated garments too. One other thing you could consider instead is something like the Mountain Equipment Switch, which is super breathable but also insulated fairly well.
Just seen the hipbelt on the Osprey rucksack. There's no way that should cause much abrasion problems. I use an Aiguille sack with a similar simple hipbelt with the same jacket and after two years mine is still looking as new.
I'd send it back - I've the same top and it's bombproof. It's been up gritstone chimneys, thrown about, and seen a fair bit of Chamonix granite and no real signs of wear.
If they won't accept it back (I'd be surprised) then the Paramo Fuera is seriously tough, but it is cut like a bin liner. The Ventile and Buffalo windshirt suggestions above will be even more durable but perhaps a bit heavier.
...However, that neglects the fact the air is a poor conductor, so the energy transfer is still dominated* by energy conducted from the body, by the fabric, and by the water itself.
* Body and air will both be radiating to the water, so it would be interesting to compare the radiated energy transfer against conducted energy transfer. My gut feel is that conduction dominates at those temperatures.
This is hideously complicated... Yes, I'd thought that as they were roughly the same contributions given their respective temperatures. That means radiation will be the same, but I'm not sure of the relative contributions of radiation and conduction here. The conduction from air would indeed be lower than through the fabric, but then this starts to depend on how wet the fabric is too...
I am sure our paths will cross at some point and we can put the world of baselayers to rights over a beer or two!