Mario / Woodys, I agree totally with your theories. I was trying to not flame Niznai , for once again handing out very questionable (IMO) information.

Basically you need it as tight as possible. As your torque is transmitted through only two tyres, it is critical to limit slippage.
On high grip surfaces , a dedicated spool makes my car wander too much at speed,though exit drive is awesome.

So I'm after a super tight ball diff, for max drive. I now have a Venom ball diff, which i'll look at modifying for durability and uprated clamp load.
Will post results...