Ahh, i goy what you mean. I did try on the bag at the store, probably brand new display pieces since i dont see any marks on it yetI can't really tell you if the leather is buff-able or not, as I luckily haven't scratched mine. However, if you've seen my earlier pictures, you'll know that I managed to get a pretty significant crease in the leather when I accidentally dropped it. Either way, the leather is delicate, and scratches are most likely going to happen.
Regarding the clasp, I don't find it to be in the way necessarily, but it does take a second to unhook it and hook it back. If you aren't paying attention when doing this, you will definitely get scratches around that area. The display models in the store had scratches around the logo from people hooking it and unhooking it. If you have long nails, it would probably be worse.
I look past the delicate nature of the 5 a 7 because it really is a beautiful, classic style in my opinion. But I probably won't ever by a smooth leather bag again.
I also have the Celine Ava in the brown/black canvas, and I love how care-free that bag is. I love both bags to be honest, but the Ava is more practical. I use the YSL when I'm a little more dressed up, and the Celine when I'm dressed casually.
Personally which one would you recommend between the two? (Celine or ysl). I am looking for something that can transition from day to night