Yea I have it too. Still un fitted though.
Im going to transfer all the suspension mods to the JDM 350z so i will fit the EDFC to that.
For Superstreet the ride on the hardest setting is not harsh at all so i think you would be ok with no edfc however with Type Flex I would recomend it. Especialy as you cant just get into adjust the rear suspension stiffness without taking the shock absorber out on our cars.
Lew