Outboard Streamers vs inboard Bartok/Rossini

I have seen limited discussion on this topic, so I would like to know what others have experienced using dedicated outboard Streamers (Innuos, etc) compared to those used in Bartok or Rossini?

Specifically, what differences were noticed (if any) and if so was an improvement heard (especially to merit the extra cost of the stand alone Streamer).

Thanks in advance!