Having spent navy sea time "up North" (-40°C and below and all that), combined with many years without a car or heated grips or any such rubbish, I have permanently damaged the nerve ends in my fingers and these days I lose all feeling at anything below +5°C or so. That makes it too dangerous to ride unprotected in winter - in fact I understand it is more dangerous to ride like that than after 4 pints of beer (howsoever politically incorrect that might be !)
So nowadays I use something more modern with heated grips and h/bar muffs in winter and leave the rest to the proper hard men (yes I know I could put them on an old bike, but I have 17 bikes, so why bother ?)
I have currently got three Landrovers and have had well over a dozen before these. I know all about Birmabrite, as that is what the body work is made of (the inner wings and underbody are un-painted and they are used all year round.)
I always found that covering bike wheel rims (chrome or aluminium) in grease or wax during winter worked quite well. They do get mega-dirty - adding to the hard man image, but clean up OK in Spring. The same trick would presumably apply to alloy mudguards. My aircraft contacts give me some wonder spray, which is excellent where alloy meets steel. It would probably as a protective coat too.
One useful trick in winter is to buy a nice new pump-up garden sprayer and keep it filled with a gallon of fresh water. As soon as you get in, wash down the bike with a spray of fresh water. Plus the little nozzle gets into all of the hard places.
Besides, winter in Paris is milder than the North of England and even better that that if we head South, so inox is un-necessary. As a Southern Jessie anyway, why would I ride to the Pennines in winter when Lyon and even M****illes are closer?
I have a particular aversion to inox fixings, whose liberal use where not originally specified has trashed the originality of too many bikes just to make them shiny and to make the parts sellers rich. The rubbish I have taken off one of my beezers beggars belief. Made out of metric hex-bar and sold by a most reputable supplier. Not to mention the plethora of inox specifications, meaning many of the fixings actually grip worse in cast alloy than cadmium, zinc or chromed fixings and then they strip threads when you take them out.
Nope, alloy it will be.