Longtime Acronym admirer here! Recently started lurking on this forum to do some research before finally purchasing my first Acronym pieces.
First piece was P27-DS, with the super convenient sliding buckles for the webbing. Second piece was P22-S, which I assumed had the same buckle system. Instead, they have the same free drawcord webbing as P23A-S, and they were falling off me in public since I tried going beltless... Had to tie the drawcords together -- this worked well, but sacrifices the dangling drawcord aesthetic and left wrinkles in the webbing.
My first solution -- went on Amazon and bought some YKK cam lock lever plastic buckles. Worked perfectly and, IMO, suited the technical aesthetic of the pants. I also bought some tri-glide buckle fasteners, very similar to the ones used by Acronym themselves in their beltless drawcord pieces, but these were useless without an extra piece of connecting webbing between the two fasteners to maintain tension and lock the sliders.
Lately, I've been using a belt with my P22-S and the P23A-S from the recent drop. I don't use the YKK buckles anymore, but they're low profile enough that you could use them in combination with your belt to keep the pants cinched up even when your belt is unbuckled. I might move to this setup myself for some piece of mind against untimely pants dropping when I'm standing at a urinal, or any other situation where I need to undo my belt without dropping my pants...