Mix in what's good for your army, there is no best set up. I use DW as Troops with normal marine support elements (Dreads and Preds) with either RW Bikers or Speeders as well and Sammael for AV14 lols.
You'd have to use your mobility and superior resilience to whittle away at the bugs. Fearless means DW/RW never want to be in assault, so they keep moving and shooting. It's a tricky army to play, but a lot of fun.Forgive me for asking but how would this split army list,lets say for example of 1500 points DW & RW compeat against a mass horde of 1500 points of tyranids? Wouldnt you be drouned in a tide of mass attacks and bodys? and and maybe some one explaine to me how this army is suposed to work?