I'm really surprised (and sad) to read that your Brixtons only lasted 6 months. This is incredibly inconsistent with my experience with Brixtons. I also never wear the heels down and have multiple pairs that I have purchased from different (authorized/legit) retailers and all have held up amazingly. Where did you purchase yours from? Gucci does do repairs, by the way, so I hope you do explore that before giving up on them!
My original pair are the off-white pair. I've had them about 6 months also and for several months (before I got multiple pairs) I wore them basically every single day and even wore them while walking around downtown to go shopping at outdoor malls and back and forth to dinner, well over half a mile to a mile of walking each way. And that pair is basically still in pristine condition, save for a teeny tiny scuff on the side that I haven't rubbed off yet (and the soles, obviously). You'd be hard-pressed to tell any discernible difference between that pair and my newer Brixtons that I've worn less than a handful of times.
Also, as an update to my earlier comment where I said that Jordaans run a half size larger than Brixtons, I have recently purchased a couple pairs of Jordaans and I wear the same size as in my Brixtons. I don't know if I misjudged when I had tried them on originally months ago and thought they were a bit larger (I'd say they're maybe 1/4 size larger than Brixton now, if anything, and fit perfect with a teeny insole in them) or if they're being made a bit smaller now, but I definitely wear a 37 in both Brixton and Jordaan. Maybe it's just the shape of my foot (I have a longer big toe than second toe), but 36.5 in either model my big toe grazes the tip of the shoe and I didn't want to risk that they wouldn't stretch at all in length or that my feet would swell any and be uncomfortable. But yes, I do agree you should try them on in-store to know for sure.
See my above feedback on how my Brixtons have lasted me. None of my Gucci loafers look anything but great, but of course how yours last will depend on a lot of factors. There are very few designer shoes I would ever wear in the rain, and Gucci loafers are not one of them. Frankly, I would highly advise against wearing ANY leather products in rain or snow, but absolutely would not wear a leather-soled shoe in those conditions. You wouldn't lay a designer purse down in the rain, would you? Why do it to your shoes then either?