I’m a fury warrior with 2 Jaithys, one is fully fed to rank 5, the other is only fed to rank 4. Currently the Rank 5 Jaithys is supposed to have a “High Chance” to compensate for providing less strength (and no secondaries) compared to the rank 4. Images of the tooltips for both my heroic Jaithys are attached showing both the Higher strength proc on Rank 4, and the “High Chance” to proc with lower strength on the Rank 5.
Jaithys Rank 4 Tooltip
Jaithys Rank 5 Tooltip
This is testable by afking on a dummy for a long period of time, in this case I did about 11 minutes and 30 seconds of just sitting there on the dummy. Thankfully details can track these as different proc ids, and while they do the same damage their buffs are different.
Current Proc Rate of Rank 5 Jaithys
Current Proc Rate of Rank 4 Jaithys
As you can see here they had a virtually identical amount of procs per minute, one with 23 the other with 22.
I would like to see other people’s test results as right now the Rank 4 Jaithys is just strictly better thank Rank 5, because not only do you keep secondaries but the strength proc is large. Meaning that since it’s irreversible, anyone who’s upgraded their has completely wasted their Jaithys.