I just made a very similar recipe I think I used too much melanoidin, 4oz sounds good for a 5 gal batch. The wort tastes awesome but I over shot the color I was looking for slightly.
10gal batch 14 plato, 1.060 OG
16lbs of Pilsner Weyermann
2lbs of Carafoam Weyermann
1lb of Melanoidin
Perle...