The quaife warranty also applies to your car even if you use it at the track which other companies simply do not provide warranty for.

Kaaz is noisy as hell (people look at you like your stupid driving around with somethign that sounds broken), Quaife is silent.

Kaaz needs to be maintained (extra cost over long term), Quaife is a sealed unit (install and forget and once off cost).

Just depends what you want from your LSD.