I think the F3.0 Tour is much more dialed in right out of the gate, whereas the 400 Tour needed to be beefed up with lead to reach max potential.
For me, the new F3.0 Tour offers some of that fast feel of modern racquets yet hasn't lost the control and touch you'd expect from Dunlop. The response is crisper, but not overly so. I liked how it played stock, but there was still ample room to add weight if desired.
The F3.0 Tour is well worth a demo in my opinion.
Hope that helps,