Both of my sons work in off-road shops. They have probably twisted around 500 trucks each by now. It is the easiest way to gain a couple of inches up front. It is a very common method of lifting late model trucks, be they Explorers, Chevys, Toyotas, Nissans, etc, all of which have torsion bar front suspension.
Like was said above -- limit the lift to 2" and no problems.
It will actually stiffen up the front suspension, as you are adding more pre-load, which acts as if you have added heavier springs. Handling wise, you will compensate for being taller by having a heavier spring rate, which for a 2" life ends up about breaking even as far as handling is concerned.
Adding taller tires into the mix will change things more, but most guys would say that the combination of a slightly stiffer suspension coupled with larger rubber on the road ends up as a better handling truck than stock. I wouldn't worry, but I would take a bit to learn how your new setup handles before I went out and tried canyon carving (and there are better vehicles for doing that than the Explorer anyway if that is your ultimate goal...).
As said above, the down side to a torsion lift is less up-travel at the wheel. By raising the suspension, you are using up what the factory built in as wheel up-travel. You will not notice this on the street, where you seldom ever use up all the wheel travel, but you will notice it on the trail if you are looking for maximum articulation. Of course, a torsion front end doesn't articulate as built anyway (at least compared to other suspension types) so there is no great loss.
Many guys have done this mod with no ill effects. I'd say go for it.
Just because you are bound to ask, the alternative to the very simple TT lift is to spend a lot of money to swap over to a better suspension. That is about the only real alternative. You either live with the 2" you can get, or check out Camburg, Superlift, Pro Comp, Fab Tech, and a couple of others. Costs begin in the $1600 range and go up from there. A cheaper alternative is to swap out the entire front suspension and axle for an earlier model straight axle (called an SAS swap - search site for info - tons of trucks done this way).
If you need more lift (or clearance) for larger tires than 31s, you can also do a 3" body lift and/or trim the fenders for tire room.
Here is a link to an easy article on this site for doing the actual TT lift.
http://www.explorer4x4.com/torsionbars.html
