Thanks to this thread I wanted to give it a shot.
I have a Gear 2 Neo and got it working with my M8 in pretty simple way.
Gear Manger .apk the latest from here:
Install the .apk and run through the setup. It will install a bunch of apks and ask to reset the Gear 2 Neo, but for me its all working great.
I did go into settings on the Gear 2 and check for the watch to be bluetooth visible. Other than that it was a snap.
I have an Factory Unlocked M8 on Att.