I have always recommended the use of Back Channels in IVC becuase it allows for an increase in interactivity, especially for those students that are shy or do not wish to interact verbally.
The use of back channels allows students to interact on a level that provides more information for the instructor on the "otherside."
But Teachers4schools posted a great article about how and when backchannels can go wrong. It is worth taking a minute to read, think about and consider prevention methods. He also shared some great resources.