Just adding my experience with the small JUC w/ diamonds I had purchased when it launched last year. I ended up returning it shortly after 3 weeks of wearing and trying to make myself love it enough to keep. More details below.
I love the JUC design but never liked the size of the regular. It is too bulky for me so the small size was perfect for my wrist. The first few days of wearing and removing it before bed, I had already noticed the bending which is problematic with the small size. It took only 8 days for the deformity to happen for me and it never got caught on anything (like clothes). It was simply just taking it off in the evening and putting it back on in the morning. When I brought this up with the after sale/repair associate, he mentioned it's going to happen and it's the nature of the bracelet design/material however there is a point where the nail and head that are no longer parallel will stop. If I kept it, I would be looking at a future of having to bring in the JUC for repair every few months and waiting few weeks for the repair to be complete. In addition, few other associates jumped in my convo with the repair associate and they were all wearing the regular size JUC. Cartier employees themselves prefer the regular over the small because of the problems they see with the small. This bracelet would work for those who will keep it on and never remove it like the love however it took 8 days for me so eventually when you do remove it and put it back on, the deformity will happen but much slower.
Wishful thinking but the best thing Cartier can do is to possibly R&D a medium size for us with the opening/closing mechanism of the regular. Obviously this will require a miracle! The associate mentioned how they couldn't do the regular mechanism on the small because of how thin it is, so they did the wire/twist on.
I checked out the thin JUC at the boutique shortly after it came out and the SA said he did not think it was sturdy enough and was prone to bending. He flat out did not recommend I purchase it, which I felt was unusual but very welcomed honesty from a SA.