The NeXgen was made directly from the Select, so in a sense they're almost the same seat when it comes to flex characteristics. The main difference from the Select to the NeXgen is driver comfort. Additional fiberglass was added primarily to the right side of the seat to better hold the driver under g-forces, and the bottom/back of the seat was reshaped to aid in the comfort of the back, specifically the lower back.
There should be no negative consequences switching to the NeXgen from the Select.