ESUG 2024 was held in Lille, and the recordings are on Youtube. Next one on the backlog.
I gave one talk that year, "A tale about scale" (slides). It's the story of ApptiveGrid going from "one laptop, me, and Pharo" (the CPM model: Computer, Pharo, Me) to about 5000 users, and everything that pulled in along the way: an issue tracker, a CI pipeline, migrations, and on the technical side a whole cascade of resilience problems. Images can crash, so you need more images, so you need a load balancer, so that machine can fail too, so you need a backup for it, and so on.
The conclusion is the part I'd stand behind again: scaling is a distraction, there's no gain without losing something, and you only do it once the benefits clearly outweigh the drawbacks. If not, don't.
Full program of ESUG 2024 can be found here.