A confession: I gave up on my previous pair of Bluetooth earbuds, Jaybird's own X2, after about a year. It wasn't their fault; they sounded good, they were comfortable, and the battery lasted long enough.
Sound quality The X4 sound really good; There's surprising oomph to the bass, New fins The updated fin style is more flexible and easier to keep clean than previous versions, IP rating They're safe in up to a meter of water for as long as 30 minutes
Goofy proprietary charger I'm more bothered than most by single-purpose cables and adapters, but come on; The charging clip is even worse than the X3's, New cinch A single cinch for adjusting the wire between the earbuds is simpler, but it negatively impacts the fit compared to the double cinch...