Suggestion:
Add more support for impedance controlled wires.
(Single ended and Differential)
For now i set the width and clearance for differential traces in the net classes.
I calculate the parameters in a excel sheet I made for this.
The calculations for this parameters a not very difficult.
(I can send the sheet if you want)
But I have to change those every time is switch to another layer.
Implementation as I thought add another field in the net classes