100% guarantee tmr is better then 50% chance to remove 20%. Obviously lots of rng to get it to land.
Jyn is great as she can do 100% tmr ever other turn.
Now to dash the hopes of the use of the new empire guys use in the Raid.
krennic:
again I think all raid bosses will be immune to Stagger, rocket man in tank raid is specifically listed as such and his fearsome foe is the only one that seems to get updated. Worth a shot to see but my guess is that he will be immune. If using tfp don't really see any other use for krennic in the team
Deathtrooper:
All raid bosses are immune to CD increases. That has been a part of fearsome foe for some time now. Death mark is considered a massive damage attack and will not do 50% Health damage. It will only do 0.1% against raid bosses not 50% that is about 4k damage vs heroic Rancor.
Not sure if the door panel counts as an opponent or not so not sure if you could even get deathmark on the rancor as there has to be a defeated enemy.