Just this: CEC, ie the control of connected devices via HDMI works flawlessly. Both when the control signal is looped before or after the adapter.
My configuration is a multimedia PC with Kodi (formerly XBMC), which was made CEC-enabled with Pulse-Eight. The splitter I needed because Kodi the audio signal only can output via HDMI or SPDIF either, but not at the same time and my 5.1 receiver does not have HDMI Input.