Yes, it's a decent system, although it can be improved. The geometry is not perfect. IT uses a single center hinge point and this does not perfectly align with the rest of the suspension. The way greenwood did it on his racers 9with short toe control links behind the halfshafts) is a better way to do it IMO.
Think of the way the C4 controls toe like how a center take off rack with center mount (close together) tie rod ends handles it. The idea is to have a link that is as long as it gets so that with suspension movement the angle doesn't change much and therefore the horizontal component's length stays within limits vs. the ideal. IE reduced angle limits the effect on the resulting horizontal component (simple vector theory)