I think a point based system without WRs would be great.
No average Lap times or something like that. It would forbid any racing for good positions in a race.
So die point based System should be based on how many FZRs and XRRs / FXRs are participating.
For example:
When one FZR is always winning and all FZRs are in front of the XRRs / FXRs and one XRR is always directly behind the FZRs then both should have the same points.
The data could be this:
5 FZR 5 XRR
->
First Place FZR 29 points
Sixth Place XRR 29 points (first place behind FZR)
but :
If the XRR finishes fifth (in front of one FZR) he should get more points.
With this system alle the FZRs would battle as well as the XRRs and the XRRs would be glad to get one or more FZRs.