I put flex forks on my Super Z.
I feel they help take some of the harshness out or the bumps.
I plan to have this mower for a long time, so I think the flex forks were worth it for me.
There is a difference but not much. I have had them on my last two mowers and they do help somewhat in achieving a smoother ride. Is the slight bit worth it? Hard to say, but I will take every little bit that helps.