Part of me wants to go SageTV because Google is now somehow associated with it?
Google actually killed SageTV as a product so that's a reason to "stick it" to Google. It took a couple of years for Google to release the source code for open source development.
I see no reason to make HDHomeRun PVR an app at all. It's a PVR, not a player. It's best implemented as a service. The interface and player are a different issue. I'd rather see a Windows desktop interface first. That would make it compatible with all current versions of Windows, not just Win8 and Win10. Making a universal app interface and player would be a bonus.