(Several people have asked whether using Wear impacts the battery life of the connected phone, by the way. I tested both watches with a Moto X and an HTC One (M8), and I haven't noticed any measurable difference in the phones' battery life as a result of the smartwatch pairing.)
Want to know how well Android Wear works?
For a thorough, deep-dive examination of Google's Android Wear interface, check out our review Android Wear deep-dive review: A smart start to smartwatch software.
Stamina aside, there's not a heck of a lot to say about performance for these two watches: The G Watch and Gear Live share the same internals, and both devices run smoothly. Apps sometimes take a few seconds to open, and there's an occasional delay for voice commands to be recognized, but neither system feels sluggish and I haven't seen any jitteriness in animations.
The only seemingly performance-related difference you'll notice in using the two watches is that the Gear Live is far more sensitive to gestures. Android Wear automatically wakes a watch and illuminates its display when you move your wrist in an upward motion. On the Gear Live, even the slightest movement will cause the display to light up. The G Watch, on the other hand, requires a more pronounced motion in order for the gesture to work.
I found the G Watch's lower sensitivity to be frustrating at first but got used to it pretty quickly. You basically just have to twist your wrist as you raise it to get the gesture to work with that device — and once you figure that out, everything's fine. The motion is a little less natural, but that also means you get less accidental activations when you're just moving your arm in a regular way.
Other points of differentiation
A few other noteworthy differences to mention before we wrap things up:
Samsung's Gear Live has a heart rate sensor on its back; LG's G Watch does not. Does that actually matter? For most people, probably not.
The Gear Live's heart rate sensor takes measurements on demand only, not continuously or at regular intervals throughout the day. It's also somewhat tricky to use: If the watch isn't positioned just right against your wrist or if your skin is slightly damp (like, you know, from sweating), you won't be able to get a reading. And its measurements vary enough to make them unreliable for anyone who really needs that sort of information.
The Gear Live's charger is, in a word, awful. It's a cheap plastic wedge that's difficult to snap onto the device's back and feels like it's going to break every time you remove it. (In fact, I've already seen a few reports on social media of chargers or even the connecting mechanisms on the watch breaking after only days of use.) This may seem inconsequential, but remember that you'll be removing the watch from the charger every morning and reattaching it every night.
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