I just got my Nismo and I'm actually thinking of replacing the suspension with Teins. It's too stiff and rides like my stock Evo 9 (which is like riding a galloping horse sometimes) I really miss my Evo's Tein Flex adjustable suspension.
My only problem is that It's no longer a Nismo tuned car when I mess with the suspension.
I think Coilovers are better.