I will have at most 100 users generating an ID in a day (on the project I am using ULIDs with). The possibility of them having a conflict with generating the ULID is so low that I don't even consider it a concern.
So, "extreme condition" is one where someone could actually generate a conflict. A realm of production I don't work in. (maybe Twitter/Facebook would have this problem)
Therefore, I feel an easier to use/work with UID like ULID is both reasonable and preferable over other options.