I wouldn't personally use it in an oatmeal stout, but most likely a high ABV Quad. I like to keep my oatmeal stouts all grain, and free from sugar additions, since the yeast I use for lower ABV stouts/porters(Wyeast 1084), tends to kick off some fusels that I don't care for, and need time to smooth out.
I would hink this candi sugar would synergize well with some toasted crystal malts, and WLP500.