Dynalite Gold is indeed a high launch shaft. You may find it better moving to a low or mid launch shaft, Dynamic Gold SL or Dynamic Gold Lite respectively. Although I would only try one club first before changing all of them.
Flex, that is harder to say. Although you hit you 8i 150 and say you have a fairly fast swing, without knowing how you load your shaft during the swing it will be a case of trial and error.
I was constantly told that I needed a stiff shaft because of my clubhead speed (again I hit an 8i about 150) and have had stiff shafts for 7 years, but after 1 round too many of struggling I went for a fitting on a True Temper shaftlab. After the fitting I was recommended a A/R flex. I had a Dynamic Gold Lite R300 fitted to a spare 6 iron and after 2 months of trying them, what a difference! I may have my irons back by the weekend and I cannot wait to take them on the course.
I can recommend a fitting on a shaftlab.
www.shaftlab.com