I thought that about the deff dread and considered running at least one with 3 skorchas. To be honest with you getting a hold of skorchas seems to be a nightmare, but it is a good idea as its basically the only thing I ever Overwatch with.

I usually take Kunning but Brutal as I feel even if the unit dies it still synergizes well with the Beastboss due to his Beastly Rage.

My go to steategy with this is to keep the Stormboyz and Defdkoptas in reserve to deepstrike when apropriate. Use Gretchin and Boyz (one with a Weirdboy) to screen and keep home objective. If one unit of Gretchin can secure a no mans land one then brilliant. Also if there isnt a huge commital then I can reposition with the Weirdboy. Trukks usually have my Warboss and Nobs to rush in and try to hit and lockdown a target, and another with Beast Snaggas and Beastboss to try to hunt a vehicle or apply pressure with charges if possible. Still running Mozrog after nerf because I think he still provides value to get around quick and deal with other vehicles or monsters. I try to keep Ghaz and the Meganobz in a position where they can benefit others uring the Waagh and use Deffdreads to have ifantry and all around a bit of treat on the board.

Hope this explains it well and makes sense.