I purchased the Garmin V3 and so far they are pretty good - no issues with syncing, updating or using. They wake up and calibrate fine and are easy to change from bike to bike. I cannot comment on the battery life as of yet but they seem pretty awesome (dispite not having all options with my edge 810).

The only issue I have with them so far is that they DO NOT line up with my Wahoo/trainer road power. The NP so far is roughly 3% lower when I tested them last. However, during the ride I did stop while my head unit continued running while I did some slight saddle adjustment so I will try again - but so far they do not read the same as my wahoo.