Go to the Ping and the True Temper (now owns PX) websites. The sites will give you weights and performance specs on the different flexes of the shafts.
You have bad info on flighted shafts. Flighted shafts have a variable kickpoint for different irons. Longer irons have a lower kickpoint to help get the ball up a bit faster, medium irons have a mid kickpoint, and short irons (8i on up) have a higher kickpoint to prevent the shots from ballooning (taking off too high).
You may be thinking of basic rifle shafts. Rifles give all clubs a little extra boost at impact/launch, but ball flight flattens out and doesn't get as high overall.
Flighted shafts like PX versions are more expensive than non-flighted. The reason: Flighted shafts require separate templates for long, medium and short iron, rather than a single template like other models. This increases manufacturing and inventory costs. (Info in this paragraph courtesy of The GolfWorks).
Note: Torque in steel shafts doesn't vary much - in some charts, it isn't listed. Torque much more a factor in graphite shafts.
Edit: Rifle info added.
Edited by WUTiger - 8/19/12 at 2:37pm