I replaced my  21 & 24 910's with the same in the 913's and as Chad said to me they were a lot easier to hit.  Played a few rounds with them in mid Nov before the courses closed and they felt and performed great for me. 

I've been using the 20* 913hd with a x100 steel shaft since mid summer 2013. Great Ball flight, can hit it high or low. Flys more like an iron vs a wood. Good feel. The small head goes through the rough easily. I have used 909 with 904Hb xstiff, before and have experimented with Razor tour. The 913hd is by far my favorite. I am even thinking of putting an 913hd 18* with a graphite shaft in the bag instead of a 5 wood. 

Currently I play the 910H 21* and 24* with the stock Diamana Kai'li shaft. I find them easy to hit out of the rough or off tight lies with nice soft landing. They have been in my bag for a while. Great clubs!