I am comparing the Stagea to my R33 GTS-t since they are more or less the same engine and I know exactly how each feels in traffic. GTR's are doggy by comparison to a GTS-t off line as well unless you get serious and/or start sidestepping the clutch.
The RS4S weighs much more than 1620kg, how much extra weight HICAS and the man sized drive shaft is worth beats me but it was well over 1700kg on the weighbridge.
Once they are rolling they go fine never get and argument from me on that score. Off the line the weight hurts them. No one can run and hide from that fact, be it 200kg more 300kg more or 400kg more.
Zorro I imagine the RB30 has transformed the car into what it should have been from factory.