Does the Z have a rear toe-steer problem?

Red__Zed

Most of the dynamic comes from the high wheel rate out back, as well as the dynamic change in rear toe mid-corner (both of which have been jacked up vs the 350)

Nissan basically improved full-on-throttle corner dynamics at the expense of off- and partial-throttle dynamic. The 350 had a tendency to step out under throttle due to insufficient toe in the rear. For the 370z, Nissan dialed in a suspension setup that would increase rear toe more significantly during cornering, and you wind up with a bit of a "floaty" or unstable feel from the excessive toe-in. You couple this with the high wheel rate, and you get exactly what you are talking about.