I have played and tested with the UK Harmony skill, Harmony Hub and Yonomi. I can turn my TV off/on via Yonomi with no issues however, I am unable to change channels (even though the Harmony skill states you can when you enable the skill) - this is simply due to the limitations of the Harmony UK skill, until we get access to the U.S skill there isn't a way to change channels. I did experiment with creating an activity to change channels with the Harmony hub but again there is a limitation to this as the first step in creating the activity MUST include turning a device on or off - there is no way to remove this step which seems a bit silly.