The lateral links are not the same length and the heights differ slightly, the bumpsteer when our was built initially was really bad we had to make lots of adjustments to dial it out, even the camber changes aren't brilliant and most of the advances in the modern cars is the increase in suspension travel and improved geometry from bump to droop...

I don't have mega experience with the difference in the later beams, but I do know that the later versions were nigh as good as the WRC configuration, mate of mine running a Group A car on Gravel car is using a later Tarmac beam with Mag Arms..subtle adjustments do overcome the problems with both setups but I do wonder how many people actually measure things like bumpsteer when they set a car up...