The Performance is not 4250lbs,
more like 4050lbs.
The motor/axles don't save that much weight, the bulk of the difference is the smaller battery. I very much doubt you'd feel the difference in weight distribution.
About 450lbs of the difference between the P and SR+ is no small change, but to feel that you'd definitely need quality rubber.
P.S. I think ND RF is a travesty, but I'm considering picking up a proper convertible ND2 as a replacement for the S2000 I'm getting bored with.