Think of a heim joint vs a rubber cleavite bushing. That is the type of thing you are trying to compare. Note the use of the words joint and bushing. If you don't understand this, then you need to study the differences between the Johnny Joint and the Duraflex bushing.
In your case, both ends by themselves are fully capable of supporting the misalignment caused by a 12" travel shock. The JJ will simply move along with the suspension. The DF bushing will need to stretch to achieve that movement. However, the JJ will misalign long before the DF feels the need to deflect. The only action that the DF bushing will do is rotate in the mount and misalign a bit side to side from the track bar shift.
The only way to get the DF bushing to do it's share is the work is to use a second DF bushing or a bonded rubber cleavite bushing.