I have the Spohn unit with poly mounted torque arm. The spherical mount will give you a lot more vibration.
Not saying the stock stuff doesn't work,..but it's not the best design. The rubber torque arm mount can flex under hard accelleration causing your pinion angle to change.
The main reason I went with one was at the same time I was swapping to a Moser Ford 9" rear and I wanted to make sure I had a way to adjust any misaligned pinion angle. When I first put it on, I also put on a poly trannsmission mount. Drove it like that for a day. The vibrations were horrible. The whole car would shake when accellerating. The next day I went to Autozone and got a stock rubber tranny mount. Put that on and the car is back to being a smooth as a stocker.
Is it stronger than the stocker? Yes. Does it improve your 60ft times? Dunno. Nobody has yet to do a back to back comparison that I know of. If you're going for consistancy, I would think it would be better than the stock, b/c there will be little to no play or flex under load like the stocker and you have the ability to fine tune the suspension for the best launches. This would come in handy if your were racing a particular class that had a limit on tire type or size.