I use them on my BMX/Dirt Jumpers, they're totally unnecessary on a track bike unless you need the half-link to really slam that back wheel or you're grinding etc.
I used Shadow Consipracy V2 and that thing constantly had to be adjusted. People talk ab half links "stretching" out, and it's true in my experience. Even w tensioners that chain would slack after every 50-60 miles.
You kidding me!? Geez. They sold me saying that they are tough with high tensile strength and stuff. Learn something everyday, huh? But why would that be? I know the sidewalls aren't stretching. For my chain (wore out and died) had crappy jagged rollers. And I thought I would get a better results with better half-link chains like Shadow Conspiracy.