Does anyone know how the empeg deals with a really stiffened suspension?

It is highly unlikely that your stiffened suspension could exceed the shock tolerances of the empeg. There are other pieces that will fall off your car before those hard drives get into trouble.

The hard drives are rated at 150 G impact while spun up, 400 G impact when not turning -- and they are spun up under normal usage only about 5% of the time.

That's the hard drives themselves. The hard drives are mounted in very clever little rubber shock absorbers inside the player. Just guessing here, but I'd guess it would take a 300 G impact on the player to give 150 G impact to the drives themselves.

There is usually a little bit of play in the way the empeg sled is mounted to the dash; and the dash will flex a little bit under impact as well, giving you yet another layer of protection for the player.

Even if you replaced all your shock absorbers with steel rods (so you had no suspension at all) there would still be considerable shock absorption from the tires themselves.

I truly believe that the player can absorb more punishment in your stiff Jetta than you can.

In the summer time I have my player installed in my bicycle where the only suspension is the flex of tires and front fork. (The empeg sits in a foam rubber cradle). That is probably more punishing than anything you could do with your car.

tanstaafl.