The torsion key lift just reindexes the the t-bars so you would have no down travel and expect to repalce ball joints, cv's, and other front susp. parts often.
The ride will be extremlly rough.
Think of it this way, jack up the front of the truck by the crossmember and the front susp. will be at full droop, now with the keys this is how the truck sits on the ground- not good.
I would recomend a body lift, it allows for bigger tires and keeps the factory ride and steering geometry.