RE: Hyper 7 torsen diff Good or Bad??
I'm not an expert but I used fioroni torsen diffs for a while and I thought they have serious issues when it comes to rutted tracks or rhythm sections. Also, they behave strangely if you have to make quick back to back turns in opposite directions. The problem is that while they do "lock" the traction wheel, it takes too long to be very useful. Most of the time, by the time it engages, you're already needing a different wheel to lock. It would probably work better on a long, smooth track where you don't need it to react so quickly.
They would probably be awsome for rock crawling since you only need one wheel on the ground to keep moving forward.