the long line isn't the point, it's the result of a higher-purchase depower system.
if you go 3:1 or 4:1, then you get fine tuning control of the kite with a lot less stength needed and can do it under load. But you end up with a long tail because you need to pull a more line for less trim. its a tradeoff. You do want it at least a certain length to reach it though .
the idea is to be able to keep perfect kite trim and perfect body position, not compromising either - like a dinghy sailor would do with a mainsheet. Sheeting in and out with the bar is more like a shock absorbing system for the micro gusts.
I've had a similar system on my bar for over a year now and it really helps.
watch closely how Adam trims his kite in this Ristafins video. http://vimeo.com/25127199