The metallic finish does rub off of bags, including YSL, with regular use and you'll usually see it on places like the handles, corners or areas that come into contact with and rub against your body. If you just pull it out once in a while or only use it for a few days at a time then the wear and tear won't be as big of a problem. Also, because this Muse has a crackled finish and isn't just completely smooth, it may hide wear better.
Overall, if having some of the finish rub off is going to be an issue for you, then I just wouldn't consider this a daily use bag. I personally tend to stay away from metallics for me because when I get a bag that I love, I'll use it daily for weeks on end and that would be pretty hard on a metallic. If having some of the finish rub off doesn't bother you, though, or you're not planning on carrying it that often, then I'd say go for it!