I think it's fair enough to discuss ABS brakes as they are an important feature of this series of test patches.
One bug report was that the "Braking - GTI" lesson text is now quite wrong and inapproriate for a car with ABS brakes. I'm thinking the XF GTI should have its ABS removed, specially as the real car which it was loosely based on does not have ABS brakes, so it was a mistake fitting it with ABS in the first place.
However, the car that the XR GT was loosely based on does have ABS brakes so from that point of view it should be there in LFS. I thought that the XF GTI had a slight advantage, because if I visit a host with XFG and XRG, most people seem to be driving an XF GTI. So I was thinking that leaving ABS on the XR GT would be good for balancing. However, I am told the XR GT is usually faster and a quick look at the hotlap tables seems to agree that this is the case. So I'm not sure about the consequences of removing it from the XF GTI and leaving it on the XR GT.
One the related subject of whether it should be there at all, I think it should definitely be fitted to those cars on which it has been enabled, except the XF GTI and possibly the XR GT (as discussed above). I'm considering the possibility of passing the ABS state of the setup to InSim so host control programs can decide what they want to do if someone uses ABS. At first sight it does seem to be a good idea to allow hosts to enforce a no ABS rule, but I have not yet looked into the code for this.