Just my two cents as someone who got the Celine mini for work
If you stuff it, it can barely fit A4 paper (with a bit of bending) with a soft folder. I personally wouldn't recommend using it with A4 paper. Just for those who might need to carry some paper around, and as a gauge to the size of the mini.
Honestly I kind of regret not getting the Micro/Nano because this bag is absolutely enormous and once you start adding stuff in it, it gets really heavy. And because of how it is constructed, the bottom and the top part will sag with time - which is why I got a bag organiser, to keep it's shape. So far it's kept it's shape well. However, adding the weight of the bag PLUS the organiser PLUS your daily essentials (ie bottle, brolly, notebook, etc) it gets really heavy. Unless you are office based I wouldn't recommend this size at all. It also is a bulky bag, and if you are on public transport during peak hours be prepared to get it knocked about a bit.
I've got the black version in pebbled leather and there are no transfers so far. I'm also about 5' 3" and it hangs exactly in the photo as posted by @Ines77.
All great things to consider. I love structured bags so the sagging is definitely something to keep in mind, especially with the larger Mini. Is your Belt from Phoebe's time or since Hedi has taken over?