So I ended up getting the Dionysus super mini, as well as the Valentino crossbody and I already had the YSL WOC and
Gucci Marmont mini in other colors so I can offer my advice:
in terms of space I would rate from smallest to largest: Gucci Dionysus SM < YSL WOC < Gucci Marmont mini < Valentino Rockstud.
The leather of the Dionysus SM is indeed quite stiff and the bag is very structured. I enjoyed wearing it on few occasions mainly weddings and outings but only because it looked super cute. I couldn’t fit my iPhone (XR and then the 13 Pro) so I had to hold it in hand and the bag would fit car keys, lipstick and card holder. I would say it is a strictly occasion and evening bag but I don’t regret purchasing because it’s so pretty and because of recent price increases.
However I would say that for a micro bag you can carry as a clutch or crossbody the YSL WOC is a better choice as it holds just enough. The other two are big enough for everyday and casual wear.
Hope this helps!