I had a lw flywheel on my 2 previous cars, one a 9lb and the other a 13lb... the 9 lb was a pain when I first got it but I got used to it... anything heavier than that is easy now. Once you get used to it, it's no big deal.
In a nutshell without going into detail, the Z gets so much chatter because stock it's not a "single mass flywheel." So when you go to an aftermarket lw single mass, it throws everything off a bit and will make some chatter.
From what I've read, the following flywheel is the best way to shave off some rotational mass lbs and get your revs up quicker, without sacrificing too much Drivability, and out of all the flywheels, has the least amount of chatter, if any at all. Some people get a small amount of chatter with it, some get none. This is the flywheel I plan on going with.
ZSpeed Performance South Bend Clutch DXD Black Nissan Infiniti Flywheel