Cavity backs are workable too

I believe I have read that the higher center of gravity helps the player with faster swing speeds keep the ball lower.  I could be wrong though.

I think GI clubs can be workable, but not as easily for better player.  The way I look at it, a GI club tends to hit the ball high and straight.  So a swing that with a "players" style club might curve, with a GI club will fly straight.  You can still curve a GI club, but you probably have to make an exaggerated move.  A player with a consistent swing may prefer to use less variation to achieve the curve.

I believe the main reason is that blades (whether they be forged or caste but that's another conversation:-)) are more consistent distance wise. Accurate and repeatable distances are paramount in the pros game. Hit 100 balls with a cavity back 7 iron and 100 balls with a blade 7 iron and the blade will give you far more consistent distances where as the CB might give a dispersion of 10 yards.

This is, of course, assuming that you are hitting the sweet spot consistently.

Muscle back irons, cavity backs, game improvement irons, it still works the same..... strike the ball with the center of the face, and the ball will start in the direction the face is pointing, and will curve relative to the face angle/path.  Where the game improvement irons differ is that off-center strikes will fly slightly less off-line because GI heads are generally built around a higher MOI, or the ability to resist twisting about it's CoG. 

 

The CoG location can shift slightly for irons, and that will have a small impact on the work-ability of an iron. It's more to do with the trajectory (height) of a shot, though, and even that can be subtle (depending on the club), so don't worry about it on shaping shots sideways.   A CoG that is higher and closer to the face will produce a lower trajectory.  A CoG low and rearward in the head will produce a higher trajectory.   

Any time you are hitting a round object with a flat surface, there is workability.  A cavity doesnt change that.

Exactly, the difference is that forged are more consistant distance wise as someone above stated. You can work the ball with a CB just as easily as a forged club. The forged also give you a more buttery feel when hit correctly. On a forged club, the power you put in is directly related to the distance you get. On CBs the ball tends to come off the face hot, they are made to launch the ball but distance control is "less" ( a relative term).

Nonsense.

Forging is a process by which the clubhead is made. Cast is the alternative process. Cavity back is a type of clubhead. A cavity back club can be either forged or cast....

 

Correct, there are forged clubs that are made for high handicappers and muslce backs that are cast.  Most wedges people buy are cast, Vokey, Cleveland, TaylorMade, PING.  But that's getting a bit off topic to continue the different metals.