I have got the Harmony 650, with a bit of trial and error have got this working quite nicely (Wife user friendly). My combination is, the Z Gemma box, Sony TV, Samsung Soundbar, Raspberry Pi, Xbox & Amazon Firestick. I created an activity for the Watch TV button which powers on the TV, Zgemma & Soundbar, I can turn up the volume on the sound bar easily and from the screen on the remote I've programmed buttons for the different HDMI channels as I found the activities for other devices just didn't work consistently.
On the remote screen I've also programmed the FileList button from the Zgemma so I can get to my recordings quickly. Taken quite a lot of effort to get the remote working as I'd like it to, but finally happy!