yeah i kept the original dual mass. Didnt want the noise from the single and there was nothing wrong with it so why replace it. I was pleasantly surprised how straight forward it was to do as well. Having never had a 350z box out before was all done just under 4 hours.
Yeah, even changed the servo, the biting point totally changed, but weighting felt pretty much the same
The only other thing I did was made sure everything in the bell housing was spotless and regreased the input shaft splines, release bearing sleeve and the contact point on the armature.