I thought the Helium Evo flexed too much and I didnt really like it. Maybe if I ordered a smaller size I would have liked the flex, but I actually bought an over-sized evo for small days and the Helium construction flexed too much for me. I didnt like it.
I am told that the Hydroshort has a more "dense core" so it will not flex as much as the previous Helium models.
I'm hoping to try one out soon!