Everywhere I have seen these discussed it has always been in a sniper rifle setup. Guys like the consistent power they offer, as well as the smooth trigger responce. And they don't seem to care about the line and external tank.
I think it has more to do with the extremely high FPS you can get out of them.
One guy was talking about getting 425fps with .6 BB's, and hitting guys at 400+ feet.
Nothing says loving, like a head shot!