Ya, Vraff is pretty much spot on. Dreads are typically fire magnets while you rush them forward to get in
cc. IF, that's a big IF, they get into
cc with non special infantry, they are going to eat lunch, but good luck getting them that far.
I've found Kans to much more flexible in terms of usefulness. And yes, grotzookas are great! Plus they are good at
cc against non special infantry as well if you feel so inclined. And you can spread 3 out to provide cover for squad behind them. Try hiding 30 boys behind one dread