Driving style
It would depend on your personal driving style. If you stick only to the road, and drive very "spirited", then go with just a rear sway bar.
If you enjoy off roading lots, plus a conservative driver, then go with the front.
You will notice the difference either way.
My 96 Explorer Sport from the factory had a decent amount of understeer (push) to it with the stock sway bars. I got a set from Saleen when they were ulta-super-discounted, but not they are no longer avalable. Now the X is much more neutral, whith a hint of understeer at high speeds.
The Front will increase the way the X turns-in when you begin a turn. It will be felt more than just a rear, but also greatly multiplies the already noticeable understeer in emergency applications and spirited driving.
The rear will help the X follow through the turns, rather than just LEAN. It is noticeable in larger turns and while carrying loads. It's not as noticeable in regular driving. It gets rid of the understeer and adds just a bit of oversteer. When off roading, be sure to disconnect it because the rear tires will not be able to follow the ground as easily with it attached. Might as well disconnect the front too.
For safety, almost all cars are now designed with understeer. The loss of control is more recoverable and more predictable. However, oversteer is prefered by many race car drivers to help steer the vehicle through the turn using the throttle. The loss of control in an emergency situation with oversteer usually is sudden and results in a spin.
My experience with the X is only from my own 2door, 2wd, 96. How your X handles and may react from the sway bars could be different than mine. My suspension knowlege and experience comes from racing cars.
If you have any more questions, feel free to email me.
-Brad
