Something my group has consistently had trouble with is recognizing where special enemies are. In Vermintide, not only did every special have a unique outline and unique sounds, but they also were larger or otherwise extremely noticeable among the throngs of enemies. This was probably helped by the fact that standard enemies were smaller than the PCs (with the exception of the dwarf), and so enemies that literally stood head and shoulders above the rank and file were visible from a distance.
Pretty much every time a special has arrived when playing the Beta, we were largely unaware where they were. They are pretty much the same size, shape, and silhouette as the hordes in front of them, so when a rank is cleared, we’re completely unprepared for the trapper who suddenly snags one of us, or thereabouts. We can clearly identify them when we can see them, but picking them out, especially for psykers who need specific line of sight, is near impossible.
Of note, our Ogryn player says they can routinely spot them, as they are tall, so I do think this is a model sizing issue.