what i lost , if i install Android 5 on my gear s?

[rojhan web]

hi guys. i see many videos that install a real android 5 on gear s ... is here anyone that test this rom? with installing it , what features we lost?

1. is still possible to see/answer Phone Calls and SMS on watch? (what about other apps)

2. is "heart beat counter" + "step counter" still usable and working?

3. is it possible to go back to original watch os?