I have two sets of CT 115’s that I was fit into at CC a few years ago. I played them with Mizuno HMP’s in S flex. I didn’t think they were stout but I now I think they do play a little stout as compared to other S shafts.
I was fitted into some P790’s a few weeks ago and tried the Nippon Pro Modus 105S. I hit them better than the Oban’s. I know because I have a LM at home and put the Oban shaft in my 7 and 8 iron. The modus fly’s straight and feels smoother to me than the Oban’s do. So now I do feel the Oban plays a bit stiffer; could just be that my swing has changed as I hit a fade with the Oban shaft now and hit a nice straight shot with the Nippon’s in the same club head.