I had return regret (is that a thing?) and in the end went back for the small. I got lucky I got it even cheaper than the 1st time (30% off on MF instead of the initially 25% off).
I have resigned myself to the fact that I will own 2 Antigona: the small is super practical & lighter for day to day while still fitting tons (full size bottle of water, my tablet etc) and the medium for work & travel at a later stage (and looks better on le but can't see myself using it super regularly. Thinking of using it in rotation with my Longchamp le pliage néo)
Ooh I meant the Celine Belt bag. A typical belt bag does not hold enough for me unfortunately
No experience with the lock unfortunately and I never saw it IRL!