No three links are easer to layout and are more simple. One has 3 links or 4 if it uses a panhard and the other has 4 links or 5 with a panhard.
Trail Slayer Samurai Coil Suspension Kit
3 link or 4 link for road racing. You can arrange your three link set up for over steer or under steer through chassis roll. Experienced crew chiefs use the three link set up as part of their set up package. In my experience if you are linking a framed truck it is easer to go with a 3 link. They didnt seem to think much of the torque arm because it has some compromises as well but it was better than a 4 link. I recommend running the top link with a fair amount of anti squat built into the adjustment and a downhill angle of around 4 to 7 degrees. All too often track bars are made out to be an enemy and thats just not the case.
That is when the torque arms first started coming out but at the time all the road race cars used 3 links. I seems your right about your observation about where shocks mount but i dont think it applies. Still the same old story 3 link if you want to do corners 4 link if you want to point it straight. There are many different types of 3 and 4 link setups out there as well. Just saying 3 or 4 links does not describe the suspensions you are investigating well enough. Theres no better method to setting the roll center height and keeping an axle laterally constrained than a track bar period.
3 link rears are very cool and if executed correctly will perform even better than a triangulated 4 link.

















