If you're getting a sweet MOP, its fine wearing daily. I wear it daily and have yet to notice anything off about it and it's been like 2 years. They say MOP will shrink but that's with LONGGGG time and you may not even notice the gap of shrinkage on the sides. Replacement for center stone is also not that expensive. $100-200 for when it does happen. Don't be afraid and just get what your heart desires.
PS: Chain on VCA is delicate, thin, and sparkles like no other. I was afraid of how thin it was too, but haven't had a problem. Very sturdy! I work out with it on too! So that says alot about it!
PPS: Cartier and VCA for these two designs are very different. Keep in mind, Cartier WILL be more sturdy considering the design and material. Even the chain is thicker!