Looking at this post and your last post I think you got interesting answers since it is hard to give advice by the metrics you are sharing with your swing stats. Of course the only way you will have true measurements is to go to a fitting. Especially if you are concerned with the stiffness of the shaft that will come up with seeing your shot shapes, speed and distances with multiple swings.

You can use general shaft dimensions and characteristics to try out at the fitting. The XP95 will be significantly lighter than DG S300 by 35 grams which is over 25% of the dog S300 weight. So that is why you will see a swing speed increase. Also with the XP shafts they are a high launching high spin shaft vs the DGs which are low launching. If that is what your iron shots need it could help make an easier swing.

Agree with Mike, you very well may need a new shaft. Short of your twin brother, any testimonial for any shaft only applies to that person. Maximizing launch, carry, and roll or stopping is individual to you and your game. I am always amazed what a good fitter can do with what I end up after what I thought would be best for me. Flex is not an industry standard and kick points help different golfers. The XP95 may be better, but not necessarily best.