I don't have derailleurs anymore, but have used WH13 spokes on several IGH wheels. They are UN-breakable IMO.
I would use them on the drive side for sure at least. The DS head is what breaks 90% of the time, as far as I have seen with others.
I have also used DT pro lock brass nipples, cost 3x as much, but are 10 times as good. IMO ... Spokes are not the place to apply good enough.
I ride at 290 lbs total on tour, 8,100 miles so far. MY SA XL-FDD front hub has 24,000 trouble free miles, with 2.3 on both sides..
My Rohloff14 has 32 straight 2.0 DT Swiss spokes that have survived so far.