As a rule, dreads are only good if you take 3 or more of them. Otherwise theyr just free good targets for your opponents anti tank stuff.
The redemptor is on the upper end of dreadnoughts for Dark Angels, but thats not actually saying much, the +1 to hit only really affects one gun, which has variable amounts of shots, making it only average. Every round you dont swing that big fist is wasted efficiency and wasted points, and to swing that big fist, you need to move, which is not awesome.
Also, 2cp is hella expensive with the recent changes, especially to use on just one model. Better off putting those points and cp into our infantry choices.
Contemptors that can take double guns are way more efficient.
I still think the twin volkites are king, but their point cost has been nerfed into the ground.
The plasma Deredeo might be a good option.
But its such a niche model, I dont think enough people have the model to actually experience if its good enough or not.