The below .gif illustrates that items in relocators, when there is a lot of them bounce, disappear, and do other strange visual things. None of this (to my knowledge) affects the actual transportation of items.

Also, for some reason, items appear to travel in pairs, not the constant steady stream I would expect. The non steady stream idea is best demonstrated by using 3+ hoppers to feed the relocators, as they output one item at a time, a feature that relocators do not currently support natively.