As far as watch mechanics are concerned, I am but a troglodyte: I wouldn't recognize a pawl wheel even if it hit me in the face. Having said that, if it really is an improvement, IWC must be applauded for going the extra mile instead of just leaving the watch as it is or (if a replacement was necessary) exchanging the parts with something they know is inferior. Omega, for example, went even further with the first iteration of their co-axial movement: the a and b versions had some teething problems and by the time they reached version d, they dropped the new movement in every watch sent in for service.
On a more general note, I believe that keeping a watch in its "original" condition when that is detrimental to its functionality (see: crumbling radium paint) is for museum curators or died-in-the-wool collectors. Meh, I'm a humble watch enthusiast and I want full functionality even from an older watch.
Consider this: you bought a decrepit 15th century chateau in the Loire valley as your vacation home. Using the "all original watch" analogy, you should leave the roof leaking, not replace the missing doors or window panes and hop over missing steps in the stairway. Some of you may also own vintage cars - do you leave them to rust, or go out of your way to make them look and work as originally intended?