I agree with you Johan, it is important to remember that unlike their corresponding DDL events, DDL triggers do execute synchronously and in the source execution context. Consequently they do always have some effect on the source process and activity.

My general rule of thumb is that you should always prefer to use DDL Event notification over DDL triggers, unless you actually do want to have some effect on the triggering process or command (such as intentionally rejecting certain Logins).