I am with Shawn on this one, I'll never go back to the 4 link. A swingarm has more advantage of a 4 link. I am not sure if anyone even builts the 4 link cars anymore ?? I run on what most people would call a down home hillbilly track weekly and its a raugh bumpy track. I've ran hardtails, triple slips, 4 links, and swingarms down it. The swingarm by far is the best. There is no more twist in the chassis with the bottom bars tied together it eliminates chassis roll.
I like Shawn now have a dual suspended car, I've yet to drive it but I am sure it'll be the smoothest car at the track I race at.