Another Android launcher? In fact, this is more underrated than Firefox OS itself for the lack of support of the common local apps and I don’t know if it will have support for HTML5 apps that you can try out similar to devices with HTML5 support today. Like Sailfish OS and Ubuntu Touch, Firefox OS can be installed on various Android devices but I guess that Sailfish OS is the better choice as it may have support for Android apps that it is more or less a secure alternative to Android OS. Another risky thing is the bricking of devices that you may need to take a caution of.
Sure, Firefox OS 2.5 may have the latest features to catch up with the current versions of Firefox web browser but I may suggest the Ubuntu Touch and Sailfish OS versions of Firefox if possible.