Looks good, though I don't see a need for dextrin personally. I have a stout that has 35 IBU, and I really like it. A little more roasted won't hurt you and a little more flaked could be tossed in there to take up the lack of dextrin malt. Why the debittered? I understand that you want the color, but not the coffee/roasted, but this is a stout and that coffee flavor is kinda needed IMO.
I always have enjoyed the idea of the two row, flaked, chocolate, roasted and then a touch of crystal to round out the flavors. You seem to have that sort of recipe and I like it.