I've done it, my phone is currently using the google female voice and my girlfriends gear 2 is using the horrible samsung one. The problem is I don't know how exactly I did it. But start here:
From the phone open settings
Click language and input
Scroll all the way to the bottom and click text to speech options
Select google instead of samsung
Click the gear button to the right of the google selection
Click install voice data
Then english (united states)
Then select "female (high quality)"
Let it finish downloading and try s voice from the watch again. You should hear the google voice instead. Thats all I did and now have the google voice. I think thats all I did lol