Preliminary results in Coles Notes: Looks like Devastate triggers a Sunder for the same keypress. You get 301 from the Sunder, and 101 + damage for the Devastate. Except it looks like the 101 is now 130 if you have no Sunders down, 150 if you have one, 170 if you have two, and so on.
Again, preliminary results. I spent a lot of time on the PTR this afternoon collecting data, but it would be very good to get independent data sets to compare.