For a JK (and I assume JL), I can personally confirm that the Dynatrac uses the same joint and is the same design, just done better (sealed, greaseable, higher quality parts). I'd always go Dynatrack over Ball Joint "Delete" (I put delete in quotes because I can't do it, it's NOT A BALL JOINT DELETE! It's just a ball joint. It's the most BS marketing name ever).Im currently building a 70" 44 for my JK and have been considering my options for balljoints. I was interested in the ball joint eliminators but after looking into the Dynatrac Prosteers, I realized they are basically the same concept with some improvements. The prosteers look like they use the same type of replaceable spherical bearing, but also have seals, are greaseable and have adjustable preload. I think for the cost of the BJE that its worth it to spend the extra cash to get the prosteers.
On the Superduty line, they do have a cool feature on the upper where it's dramatically stronger than an OEM stud and essentially impossible to break. That upper is the weak link on the 05+ superduty ball joints.