I use fleece for sport, for several reasons:
It's light, so I don't really feel it when it's on, nor when it's in my bag when it starts getting warmer.
It stretches, perfect for moving around.
It breathes really well, which is nice after having overheated down that bad snow.
It dries fast, if it's gotten damp in my bag during a snowstorm and I decide to put it back on because I'm getting a bit cold, it just dries on me in a few minutes.
It isn't bulky like snugpack jackets (Polartec Thermal Pro is only 2-3mm thick, but the snugpack ones I saw were really bulky).
And yes, according to the temperature ratings of Snugpack jackets, fleece
is as warm (well can be according to the type, mostly the fluffy ones)
I can recommend Polartec fleece, especially Thermal Pro, even nicer, softer, warmer and lighter than the classic stuff!
My fleece jumper combined with a base layer and my Helly Hansen jacket have kept me warm and happy all winter, in temperatures ranging from -15° to +5°, with sometimes strong winds, in snow storms or sunny weather :-D (well, that's in the colder temperatures ; I only wore a T-shirt under the shell when it was +5, what a horrible temperature to ski in :-( )
I don't know how it would be for anything fire-related, since I can't bring myself to do anything else than ski in Winter...I must be addicted to snow

But with something ontop to stop wind and protect it from the fire it should be fine. (off topic: is the M65 wind proof?)
Oh yeah, I prefer the non-windproof type, they're lighter, dry faster and are more supple, and you can use the vents of the jacket to cool down a bit (with a windproof fleece they would be useless).
Down is also nice as an insulation layer, I use a down vest in summer for walking, because they pack down really small and are very light for the warmth, which is ideal since it lives in my bag most of the time (I only get it out at cold summits. I wouldn't like it for skiing though...
Schöffel make nice fleece jackets, and Haglöfs look and feel nice too (I've got a Corniche jacket in Thermal Pro, which is softer and lighter than my mother's Schöffel (also Thermal Pro), but I haven't tested it yet in cold conditions, so for the moment it just looks and feels nice, and is well designed.
Beyond Fleece make custom fleeces and softshells for a nice price (less than most production ones), but only have Classic 200 as non-windproof fleece. Land's End make very well priced stuff, which is good quality in my experience (it's where my mother orders most of our clothes...), and have their own fleece made by Malden Mills (Polartec). They also sell the overstocks really cheap, my down vest only cost $20 and my mother got herself a 700cuin (I think) down jacket in Dryloft, ripstop construction with reinforced shoulders, a snow skirt and all the things you could want for less than $40 (plus it outperforms her best friend's that cost ten times that [with no exageration]), and also a few windproof fleece things (marinac vest and jacket) for not much either. Well anyway, the overstocks are worth a look! (and their
fleece jacket even when not on sale only costs $40.
Lots of stuff to choose from out there!