I've found the call quality to be substantially better and, like you've said, have had no noticeable depreciation in battery life. I just wished they looked a bit better aesthetically. I've had a couple of people say that they thought I was wearing some sort of hearing aid...

I have the same Jabra headphones with my iPhone X and MBP. Great product. Jabra is a calls-first company, so the talk clarity is incredible, and the Bluetooth pairing is strong enough to walk between rooms.

The very best feature, though, is that they’re much less conspicuous than AirPods. AirPods are a visual distraction.

What would be the reason that one model of wireless earphones would have worse battery wear-out than another? Wouldn't it depend almost entirely on how many recharge cycles the battery gets? If so, then I suppose it would only depend on the battery life of the earphones (if we hold the usage rate constant).

It’s just a matter of time though. Li-ion batteries are typically rated for 500-1000 recharge cycles.